Modern Template Consolidation Engine for EJS, Markdown, Pug, Nunjucks, Liquid, and Handlebars
npm install ecto!Ecto
-----
Ecto is a modern template consolidation engine that enables the best template engines: EJS, Markdown, Pug, Nunjucks, Mustache, Handlebars, and Liquid. It consolidates these template engines to a single library, allowing you to use any of them with ease.
* Zero Config by default but all properties exposed for flexibility. Check out our easy API.
* Async render and renderFromFile functions for ES6 and Typescript.
* Render via Template File with Automatic Engine Selection. No more selecting which engine to use, engine choice is automatically decided based on the file extension.
* Only the Top Template Engines: EJS, Markdown, Pug, Nunjucks, Mustache, Liquid, and Handlebars.
* FrontMatter Helpers .hasFrontMatter, .getFrontMatter, and .removeFrontMatter for Markdown files.
* Maintained with Monthly Updates!
The Node.js package manager documentation provides the commands needed to complete the install on Windows and other operating systems.
1. Open the terminal for your project and run npm install to ensure all project dependencies are correctly installed.
``
npm install ecto
2. Declare and Initialize.
`javascriptecto
import { Ecto } from ;
const ecto = new Ecto();
`
5. Render via String for EJS (Default Engine)
`javascript`
const source = "Hello <%= firstName%> <%= lastName %>!
";
const data = {firstName: "John", lastName: "Doe"}
ecto.render(source, data).then((output) => {
console.log(output);
});
After running your program you should see the following output:
`Hello John Doe!
------
You can easily set a different defaultEngine, here we use Handlebars.
`javascriptecto
import { Ecto } from ;
const ecto = new Ecto({defaultEngine: "handlebars"});
let source = "
To render from a template file, Ecto uses the
function. This performs an automatic selection of the engine based on the file extension.`javascript
import { Ecto } from ecto;
const ecto = new Ecto();
let data = { firstName: "John", lastName: "Doe"};
//async renderFromFile(filePath:string, data?:object, rootTemplatePath?:string, filePathOutput?:string, engineName?:string): Promise
await ecto.renderFromFile("./path/to/template.ejs", data); // returns Hello John Doe!
`Only the Top Template Engines and Their Extensions
We focus on the most popular and well-maintained consolidation engines. Unfortunately other engines suffered from packages that were unsupported, making it difficult to validate them as working fully. Some engines also had limited types and lacked ease of use.
Our goal is to support the top engines, handling the vast majority of use cases. Here are the top engines that we support:
| Engine | Monthly Downloads | Extensions |
| ---------- | ---------------------------------------------------------------------------------------------- | ----------------------- |
| EJS |  | .ejs |
| Markdown |  | .markdown, .md |
| Pug |  | .pug, .jade |
| Nunjucks |  | .njk |
| Mustache |  | .mustache |
| Handlebars |  | .handlebars, .hbs, .hjs |
| Liquid |  | .liquid | |
_The
are listed above for when we Render from File._API - Methods and Parameters
The API is focused on using the main Ecto class:`javascript
const ecto = new Ecto();
//ecto. -- functions and parameters
`There are a couple of options that can be passed to the Ecto constructor:
| Name | Type | Description |
| ---------------- | ------ | ------------------------------------------------------------ |
| defaultEngine | string | This is the default engine to use if it is not set when doing rendering |
| engineOptions | object | The options for each engin that you can set initially. |
here is an example of setting the default engine and also options for
:`javascript
const ecto = new Ecto({defaultEngine: "nunjucks", engineOptions: {nunjucks: {autoescape: true}});
`When looking at the API there are two main methods to make note of:
render (async) - Render from a string.
renderFromFile (async) - Renders from a file path and will auto-select what engine to use based on the file extension. It will return a
of the rendered output.Render From String
As we have shown in Getting Started -- It's that Easy! You can render in only a couple of lines of code.
render and renderSync (
async) - Render from a string. Here is the render function with all possible arguments shown:| Name | Type | Description |
| ---------------- | ------ | ------------------------------------------------------------ |
| source | string | The markup/template source to be rendered. |
| data | object | The data to be rendered by the file. |
| engineName | string | Used to override the
Ecto.defaultEngine parameter. |
| rootTemplatePath | string | The root template path that is used for partials and layouts. |
| filePathOutput | string | Used to specify the file path, if you want to write the rendered output to a file. |Here is the simplest example of a render function. We are also showing the required steps you need to take beforehand such as setting up Ecto.
`javascript
const ecto = new Ecto();const source = "
Hello <%= firstName%> <%= lastName %>!
";
const data = {firstName: "John", lastName: "Doe"};
await ecto.render(source, data); //returns Hello John Doe!
`If you want to do synchronous rendering, you can do so by using the
function. This function takes the same parameters as the render function.`javascript
const ecto = new Ecto();
const source = "Hello <%= firstName%> <%= lastName %>!
";
const data = {firstName: "John", lastName: "Doe"};
ecto.renderSync(source, data); //returns Hello John Doe!
`Now let's say your desired engine is not EJS, you will need to specify it explicitly. You can either set the defaultEngine parameter, or simply pass it in the
function. In this case with the popular engine, Handlebars:`javascript
const ecto = new Ecto();const source = "
Hello {{firstName}} {{lastName}}!
";
const data = {firstName: "John", lastName: "Doe"}
ecto.render(source, data, "handlebars").then((output) => {
console.log(output);
});`The
and renderSync function also can handle partial files for standard engines (markdown excluded) by simply adding the rootTemplatePath:`javascript
const ecto = new Ecto();const source = "
Hello <%= firstName%> <%= lastName %>!
<%- include('/relative/path/to/partial'); %>";
const data = {firstName: "John", lastName: "Doe"};
ecto.render(source, data, undefined, "./path/to/templates").then((output) => {
console.log(output);
});`With
and renderSync you can also write to a file. This is accomplished by specifying the filePathOutput parameter as below. It will still return the output as a string:`javascript
const ecto = new Ecto();const source = "
Hello <%= firstName%> <%= lastName %>!
";
const data = {firstName: "John", lastName: "Doe"};
ecto.render(source, data, undefined, undefined, "./path/to/output/file.html").then((output) => {
console.log(output);
});
`Notice the
value passed into the engineName parameter. This is done because we already have the defaultEngine set to EJS. If you want you can easily add it in here too.-----
Render From File
To render via a template file, it is as simple as calling the
renderFromFile or renderFromFileSync function with a couple of simple parameters passed in. renderFromFile (
async) or renderFromFileSync (synchronous) - Renders from a file path and will auto-select what engine to use based on the file extension. It will return a Promise of the rendered output. One of the main benefits is that it will automatically select the correct engine based on the file extension. The renderFromFile function takes the following parameters:| Name | Type | Description |
| ---------------- | ------ | ------------------------------------------------------------ |
| filePath | string | The file that you would like to render. |
| data | object | The data to be rendered by the file. |
| rootTemplatePath | string | The root template path that is used for
partials and layouts. |
| filePathOutput | string | Used to specify the file path if you want to write the rendered output to a file. |
| engineName | string | Used to to override the auto-selection of the engineName. |This simple example showing the
renderFromFile or renderFromFileSync function shows you the bare minimum required to execute this function successfully, we are passing in the template and it will return a string. One of the main benefits is that it will automatically select the correct engine based on the file extension.
`javascript
const ecto = new Ecto();
const data = { firstName: "John", lastName: "Doe"};await ecto.renderFromFile("./path/to/template.ejs", data); // returns
Hello John Doe!
`To do this synchronously, you can use the
function. This function takes the same parameters as the renderFromFile function.`javascript
const ecto = new Ecto();
const data = { firstName: "John", lastName: "Doe"};await ecto.renderFromFileSync("./path/to/template.ejs", data); // returns
Hello John Doe!
`In this example, we are writing the output to a HTML file:
javascript
const ecto = new Ecto();
const data = { firstName: "John", lastName: "Doe"};await ecto.renderFromFile("./path/to/template.ejs", data, undefined, "./path/to/output/yourname.html")
`Notice that in these examples it is using the
to specify EJS for the rendering. You can override the auto-selected engine by passing in the string value of a template engine as a parameter into the
renderFromFile function. We pass in pug, which states we want to render the template using the Pug engine.`javascript
const ecto = new Ecto();
const data = { firstName: "John", lastName: "Doe"};ecto.renderFromFile("./path/to/template.ejs", data, undefined, "./path/to/output/yourname.html", "pug");
`Default Engine
This string parameter can be used to set the default template engine for an instance of the Ecto class. Ecto has been designed to support all major engines.
is set by default to EJS.If you would like to change the template engine there are several options available to users when setting the value of defaultEngine:Set the engine in the arguments of the Ecto constructor
One option for setting the default engine, is to do so in the Ecto constructor:
-
const ecto = new Ecto({defaultEngine: "ejs"});
-
-
-
-
-
- Set the default engine as a parameter
We can also set the default engine as a parameter, like so:
javascript
const ecto = new Ecto();
ecto.defaultEngine = "mustache";
`Alternatively, we can set the engine directly on the constructor. This would make our previous example:
javascript
const ecto = new Ecto({defaultEngine: "liquid"});
ecto.defaultEngine = "mustache";
`Set the engine as a parameter on the render function
You can explicitly override the Ecto.defaultEngine parameter in the render function:
javascript
const ecto = new Ecto();
const source = "Hello {{firstName}} {{lastName}}!
";
const data = {firstName: "John", lastName: "Doe"};
await ecto.render(source, data, "handlebars"); //returns Hello John Doe!
`Override the auto selection on renderFromFile
The
function automatically decides on the template engine, based on the file extension in the file path you specify. However, you can also explicitly set the engine you would like to use. Here we set the engine to be Pug.`javascript
const ecto = new Ecto();
const data = { firstName: "John", lastName: "Doe"};
await ecto.renderFromFile("./path/to/template.ejs", data, undefined, "./path/to/output/yourname.html", "pug"); // returns Hello John Doe!
`To make it easier to access and change between engines, all supported engines are provided as parameters on the
class as Ecto.javascript
const ecto = Ecto();
console.log(ecto.Handlebars.name); // will return "handlebars"
console.log(ecto.Handlebars.opts); // will return "handlebars" options object
`To access a specific engine you can do so by going to
and setting the SafeString:`javascript
const ecto = Ecto();
ecto.Handlebars.engine.SafeString("HTML Content!");
`Find Template Without Extension - Helper Methods
We have added in a couple of helper methods to make it easier to find a template without the extension. This is useful when you want to find a template without the extension. For example, if you have a template called
and you want to find it without the extension, you can use the findTemplateWithoutExtension for async or findTemplateWithoutExtensionSync function. This function takes two parameters:| Name | Type | Description |
| ---------------- | ------ | ------------------------------------------------------------ |
| filePath | string | The file that you would like to find without the extension. |
| templateName | string | The name of the template you would like to find. |
`javascript
const ecto = new Ecto();
const templateFilePath = ecto.findTemplateWithoutExtensionSync("./path/to/", "index");
`This will return the full path of the template based on what extension is there such as
.Markdown Example
Markdown does not contain complexities such as data objects, or partials and layouts. To render markdown its as simple as:
`javascript
const ecto = Ecto();
const source = "# markdown rulezz!";
await ecto.render(source, undefined, "markdown"); //should be markdown rulezz!
`
Render by Markdown file:javascript
const ecto = Ecto();
await ecto.renderByFile("/path/to/file.md");
`We are using Writr which is remark with all the plugins and features you need.
Handlebars Example
In Ecto we use the Fumanchu engine to render
and handlebars related templates. This is because handlebars is based on mustache with just more additional features. Fumanchu includes handlebar engine with helpers.`javascript
const ecto = Ecto();
const source = "{{year}}";ecto.render(source, undefined, "handlebars").then((output) => {
console.log(output)
});
`
Engine Mappings
Ecto contains a mapping class containing all of the engines registered in the system. The class has been designed to allow users to edit existing engine mappings. Let us explore this class in detail.
The
object has the following structure: Map- The first element of the tuple is the name of the map, such as "handlebars".
* The second element of the tuple is an array of the extensions for that map, example values may include "handlebars", "hbs","hjs".
From here you can start setting and editing engine mappings.
Setting an engine mapping - set(name:string, extensions:Array<string>): void
To set an engine mapping with extensions simply write:
mappings.set("handlebars", ["handlebars","hbs","hjs"]);
This sets the handlebars engine to accept files with the following file extensions:
* .handlebars
* .hbs
* .hjs
Delete an engine mapping - delete(name:string): void
To delete a mapping entirely you can use the
method.`
mappings.delete("handlebars");
This will remove this engine mapping entirely.
Delete an extension - deleteExtension(name:string, extension:string): void
To delete an extension for a particular engine mapping, you can use the
method. This method takes two arguments:*
name:string - the name of the engine you would like to delete the extension for.
* extension:string - the extension you would like to delete.The following code deletes two of the extensions for our
handlebars engine mapping. `
mappings.deleteExtension("handlebars", "hbs","hjs");
After executing this code the only accepted file extension for the Handlebars engine will be
.Other useful methods include
get and getName.get method - get(name:string): Array<string> | undefined
The
get method takes one argument, name:string , and will return the extensions for the name you specify. If extensions are found, they are returned as an Array. If no engine mapping can be found for the name you specify, undefined is returned. To use the get method simply write:
`
mappings.get("handlebars")
This will retrieve the array of extensions assigned to the Handlebars engine.
getName method - getName(extension:string): string | undefined
The
method takes a single argument, extension:string. If a valid extension is given, this method will return the name of the engine mapping that the extension belongs to. For example:`
mappings.getName("hjs")
This will return the string “handlebars”, which is the corresponding engine for this extension. If no match can be found, this method will return
.Gaining an understanding of this class will provide you with more options and possibilities when using Ecto.
Detect Template Engine
Ecto provides a
detectEngine method that can automatically detect the template engine from a template string by analyzing its syntax patterns. This is useful when you receive template content but don't know which engine it uses.detectEngine(source: string): string
The
detectEngine method analyzes the template syntax and returns the detected engine name. If no specific template syntax is found, it returns the configured default engine.| Name | Type | Description |
| ------ | ------ | ------------------------------------------------- |
| source | string | The template source string to analyze |
Returns: The detected engine name ('ejs', 'markdown', 'pug', 'nunjucks', 'handlebars', 'liquid') or the default engine if no specific syntax is detected.
$3
`javascript
const ecto = new Ecto();// Detect EJS templates
const ejsEngine = ecto.detectEngine('<%= name %>');
console.log(ejsEngine); // 'ejs'
// Detect Handlebars templates
const hbsEngine = ecto.detectEngine('{{name}}');
console.log(hbsEngine); // 'handlebars'
// Detect Markdown
const mdEngine = ecto.detectEngine('# Hello World\n\nThis is markdown');
console.log(mdEngine); // 'markdown'
// Detect Pug templates
const pugEngine = ecto.detectEngine('div.container\n h1 Hello');
console.log(pugEngine); // 'pug'
// Detect Nunjucks templates
const njkEngine = ecto.detectEngine('{% block content %}Hello{% endblock %}');
console.log(njkEngine); // 'nunjucks'
// Detect Liquid templates
const liquidEngine = ecto.detectEngine('{% assign name = "John" %}{{ name | upcase }}');
console.log(liquidEngine); // 'liquid'
// Returns default engine for plain text
const defaultEngine = ecto.detectEngine('Plain text without template syntax');
console.log(defaultEngine); // 'ejs' (or whatever is set as defaultEngine)
`$3
The
method recognizes the following syntax patterns:- EJS:
<% %>, <%= %>, <%- %>
- Handlebars/Mustache: , {{# }}, {{> }}
- Pug: Indentation-based syntax without angle brackets
- Nunjucks: , {% extends %}, {% include %}
- Liquid: , {% capture %}, pipe filters {{ var | filter }}
- Markdown: Headers , lists, code blocks, links, tablesNote: For ambiguous syntax (like simple
{{ }} which could be Handlebars, Mustache, or Liquid), the method makes intelligent decisions based on additional context clues in the template.
The Template Engines We Support
A template engine is a tool that allows developers to write HTML markup that contains the template engine’s defined tags and syntax. These tags are used to insert variables into the final output of the template, or run some programming logic at run-time before sending the final HTML to the browser for display.
EJS
EJS stands for Embedded JavaScript. It is a templating engine that allows users to generate HTML using plain JavaScript.
You define HTML pages in the EJS syntax and specify where various data will be shown on the page. Then, your application combines data with the template and "renders" a complete HTML page where EJS takes your data and inserts it into the web page according to how you've defined the template. For example, you could have a table of dynamic data from a database and you want EJS to generate the table of data according to your display rules. It saves you from the writing code and logic to dynamically generate HTML based on data.
It is a tool for generating web pages that can include dynamic data and can share templated pieces with other web pages. It is not a front-end framework. While EJS can be used by client-side Javascript to generate HTML on the client-side, it is typically used by your back-end to generate web pages in response to some URL request. EJS is not a client-side framework like Angular or React.
Markdown
Markdown is a lightweight markup language that you can use to add formatting elements to plaintext text documents. Markdown is now one of the world’s most popular markup languages.
Using Markdown is different from using a word and text editor. In an application like Microsoft Word, you click buttons to format words and phrases, and the changes are visible immediately. Markdown isn’t like that. When you create a Markdown-formatted file, you add Markdown syntax to the text to indicate which words and phrases should look different.
There are several reasons why people might choose Markdown instead of standard text editors.
* Markdown has a wide range of potential uses. It can be used to create websites, documents, notes, books, presentations, email messages, and technical documentation.
* Files containing Markdown-formatted text can be opened using virtually any application. This differs greatly from word processing applications like Microsoft Word that lock your content into a proprietary file format.
* You can create Markdown-formatted text on any device running any operating system.
* Markdown is future proof. Even if the application you’re using stops working at some point in the future, you’ll still be able to read your Markdown-formatted text using a text editing application.
* Markdown is widely supported. Websites like Reddit and GitHub support Markdown, along with many other desktop and web-based applications.
PUG
Pug.js is an HTML templating engine that takes simple Pug code, which the Pug compiler will compile into HTML code that browsers can understand. Some features and advantages of the Pug template engine are as follows:
* Pug has powerful features like conditions, loops, includes, that allows us to render HTML code based on user input or reference data.
* Pug supports JavaScript natively.
* Pug is excellent for handling dynamic, changing data. Imagine we have an email template, with certain fields to be customized depending on who you are sending the email to. Before sending the email we can compile the Pug code to HTML, using the user data to fill the gaps where the dynamic information should go.
Nunjucks
Nunjucks is a rich and powerful template engine for JavaScript. Nunjucks is developed by Mozilla and maintained by the Node JS Foundation. Nunjucks can be used in both Node and the browser.
In Node, Nunjucks is installed using npm. It is rich, fast, extensible, and available everywhere. It's highly optimized at just 8kb gzipped.
Some of the advantages of using Nunjucks for your project are:
* It is a rich templating language with block inheritance, auto-escaping, macros, asynchronous control, and more.
* Nunjucks is fast, lean, and highly-performant.
* Easily extensible with custom filters and extensions.
* Available in Node and all modern web browsers, along with precompilation options.
Mustache
Mustache is a logic-less template syntax. It can be used for HTML, config files, source code, and more. It is often referred to as “logic-less” as there are no if statements, else clauses, or for loops. There are only tags. Tags are replaced with actual values at runtime.
Mustache.js is an implementation of the mustache template system in JavaScript. It is often considered the base for JavaScript templating. Since mustache supports various languages, we don’t need a separate templating system on the server side.
`javascript
Mustache.render("Hello, {{name}}", { name: "John" });
// returns: Hello, John
`
We see two braces around
. This is Mustache syntax to show that it is a placeholder. When Mustache compiles this, it will look for the “name” property in the object we pass in, and replace {{ name }} with the actual value, in this case, “John”.Mustache is not actually a templating engine. Mustache is a specification for a templating language. In general, we would write templates according to the Mustache specification, and they can then be compiled by a templating engine to be rendered, eventually creating an output.
Handlebars
Handlebars is a simple templating language. It uses a template and an input object to generate HTML or other text formats. Handlebars templates look like regular text with embedded Handlebars expressions. Handlebars expressions are wrapped in double curly braces, like this:
{{expression}}. We use @jaredwray/fumanchu as it contains handbars and helpers.
`javascript
const ecto = Ecto();
const source = "{{year}}";await ecto.render(source, undefined, "handlebars"); //returns current year as a number
`Liquid
Some refer to Liquid as a template language, while others may call it a template engine. It doesn't really matter which label you apply, in many ways both are right. It has a syntax (like traditional programming languages), has concepts such as output, logic, and loops, and it interacts with variables and data, just as you would with a language such as PHP.
Liquid, like the previous template engines, creates a bridge between an HTML file and a data store. It does this by allowing us to access variables from within a template, or the Liquid file, with a simple and readable syntax.
Liquid files have the extension of
. A liquid file is a mix of standard HTML code and Liquid constructs. Its clear syntax is easy to distinguish from HTML when working with a Liquid file. This is made even easier thanks to the use of two sets of delimiters.The double curly brace delimiters
{{ }} denote output, and the curly brace percentage delimiters {% %} denote logic. You'll become very familiar with these as every Liquid construct begins with one, or the other. Another way of thinking of delimiters is as placeholders. A placeholder can be viewed as a piece of code that will ultimately be replaced by data when the compiled file is sent to the browser.FrontMatter Helper Functions
Ecto has added in some helper functions for frontmatter in markdown files. Frontmatter is metadata that is at the top of a markdown file. It is used to store information about the file such as the author, date, tags, and license.
*
.hasFrontMatter(source: string): boolean - This function checks if the markdown file has frontmatter. It takes in a string and returns a boolean value.
* .getFrontMatter(source: string): object - This function gets the frontmatter from the markdown file. It takes in a string and returns an object.
* setFrontMatter(source:string, data: Record - This function sets the front matter even if it already exists and returns the full source with the new front matter.
* .removeFrontMatter(source: string): string - This function removes the frontmatter from the markdown file. It takes in a string and returns a string.Caching on Rendering
Ecto has a built-in caching mechanism that is
disabled by default that allows you to cache the rendered output of templates. This is useful for improving performance and reducing the number of times a template needs to be rendered. There are currently two caching engines available: MemoryCache and FileCache.
* cache - This is the default caching engine and it uses in-memory by default but is called async so you can use a storage layer such as Redis or PostgreSQL. This is done using Cacheable which is a high performance caching library.
* cacheSync - This is the synchronous version of the cache engine and uses CacheableMemory. It is useful for when you need to render a template synchronously and cache the output.Here is an example of how to use the caching engine with
render:`javascript
import { Ecto } from 'ecto';const ecto = new Ecto({ cache: true });
const source = "
Hello <%= firstName%> <%= lastName %>!
";
const data = { firstName: "John", lastName: "Doe" };
const result = await ecto.render(source, data);
console.log(result); // Hello John Doe!
`You can also use the
engine with renderSync:`javascript
import { Ecto } from 'ecto';
const ecto = new Ecto({ cacheSync: true });
const source = "Hello <%= firstName%> <%= lastName %>!
";
const data = { firstName: "John", lastName: "Doe" };
const result = ecto.renderSync(source, data);
console.log(result); // Hello John Doe!
`If you want to provide your own caching configuration, you can do so by passing
instance to the Ecto constructor:`javascript
import { Ecto } from 'ecto';
import { Cacheable } from 'cacheable';
const cacheable = new Cacheable({
// Your caching configuration here
});
const ecto = new Ecto({ cache: cacheable });
const source = "Hello <%= firstName%> <%= lastName %>!
";
const data = { firstName: "John", lastName: "Doe" };
const result = await ecto.render(source, data);
console.log(result); // Hello John Doe!
`Emitting Events
Ecto has a built-in event emitter that allows you to listen for events that occur during the rendering process. This is useful for debugging and monitoring the rendering process. The following events are emitted:
-
- Emitted when a cached result is found and returned.
- cacheMiss - Emitted when a cached result is not found and the template needs to be rendered.
- info - Emitted for informational messages.
- warn - Emitted for warning messages.
- error - Emitted for error messages.You can listen for these events by using the
on method of the Ecto instance:`javascript
import { Ecto } from 'ecto';
const ecto = new Ecto();
ecto.on('cacheHit', (data) => {
console.log('Cache hit:', data);
});
ecto.on('cacheMiss', (data) => {
console.log('Cache miss:', data);
});
ecto.on('warn', (data) => {
console.warn('Warning:', data);
});
ecto.on('error', (data) => {
console.error('Error:', data);
});const source = "
Hello <%= firstName%> <%= lastName %>!
";
const data = { firstName: "John", lastName: "Doe" };
await ecto.render(source, data); // Hello John Doe!
`Hooks
Ecto supports hooks that allow you to intercept and modify data during the rendering process. Unlike events (which are notifications only), hooks let you transform the source, data, or result as it flows through the render pipeline.
Available Hooks
| Hook Name | Description |
| --------- | ----------- |
|
| Called before async rendering. Allows modifying source and data. |
| afterRender | Called after async rendering. Allows modifying the result. |
| beforeRenderSync | Called before sync rendering. Allows modifying source and data. |
| afterRenderSync | Called after sync rendering. Allows modifying the result. |Hook Context
The
beforeRender and beforeRenderSync hooks receive a RenderContext object:`typescript
type RenderContext = {
source: string; // Template source (modifiable)
data?: Record; // Template data (modifiable)
engineName: string; // Engine being used
rootTemplatePath?: string; // Root path for partials
filePathOutput?: string; // Output file path
cached: boolean; // True if result came from cache
};
`The
and afterRenderSync hooks receive a RenderResult object:`typescript
type RenderResult = {
result: string; // Rendered output (modifiable)
context: RenderContext; // Original render context
};
`Using Hooks
Register hooks using the
method:`javascript
import { Ecto, EctoEvents } from 'ecto';const ecto = new Ecto();
// Modify source before rendering
ecto.onHook(EctoEvents.beforeRender, (context) => {
context.source = context.source.replace('{{placeholder}}', '{{replaced}}');
});
// Inject data before rendering
ecto.onHook(EctoEvents.beforeRender, (context) => {
context.data = { ...context.data, injectedValue: 'hello' };
});
// Transform result after rendering
ecto.onHook(EctoEvents.afterRender, (renderResult) => {
renderResult.result = renderResult.result.toUpperCase();
});
// Check if result was cached
ecto.onHook(EctoEvents.afterRender, (renderResult) => {
if (renderResult.context.cached) {
console.log('Result came from cache');
}
});
const output = await ecto.render('<%= name %>', { name: 'World' });
`Sync Hooks Example
javascript
import { Ecto, EctoEvents } from 'ecto';const ecto = new Ecto();
// Works the same for sync rendering
ecto.onHook(EctoEvents.beforeRenderSync, (context) => {
context.data = { ...context.data, timestamp: Date.now() };
});
ecto.onHook(EctoEvents.afterRenderSync, (renderResult) => {
renderResult.result =
\n${renderResult.result};
});const output = ecto.renderSync('<%= name %>', { name: 'World' });
`Multiple Hooks
Multiple hooks for the same event are executed in the order they are registered:
javascript
ecto.onHook(EctoEvents.beforeRender, (context) => {
console.log('First hook');
context.source += ' - modified by first';
});ecto.onHook(EctoEvents.beforeRender, (context) => {
console.log('Second hook');
context.source += ' - modified by second';
});
`Creating Custom Engines
Ecto allows you to create your own custom template engines by implementing the
. This is useful when you want to integrate a template engine that isn't built into Ecto or when you need custom rendering logic.Direct Engine Usage
All built-in engines can be imported and used directly without going through the main
Ecto class:`typescript
import { EJS, Handlebars, Liquid, Markdown, Nunjucks, Pug } from 'ecto';// Use any engine directly
const handlebars = new Handlebars();
const result = await handlebars.render('Hello {{name}}', { name: 'World' });
`$3
The recommended way to customize engines is through the
parameter in the Ecto constructor:`typescript
import { Ecto } from 'ecto';const ecto = new Ecto({
engineOptions: {
handlebars: {
noEscape: false,
strict: true
},
markdown: {
html: true,
breaks: true
},
ejs: {
delimiter: '?' // Use instead of <% %>
}
}
});
// Engines are now configured with your options
await ecto.render('', { name: 'World' }, 'ejs');
`$3
After creating an Ecto instance, you can access each engine directly and modify it. This is useful for adding custom helpers or changing settings dynamically:
typescript
import { Ecto } from 'ecto';const ecto = new Ecto();
// Access the Handlebars engine and add custom helpers
ecto.handlebars.engine.registerHelper('uppercase', (text) => {
return text.toUpperCase();
});
ecto.handlebars.engine.registerHelper('formatDate', (date) => {
return new Date(date).toLocaleDateString();
});
// Now use the customized engine
const result = await ecto.render(
'Hello {{uppercase name}} - {{formatDate date}}',
{ name: 'world', date: '2024-01-15' },
'handlebars'
);
// Output: Hello WORLD - 1/15/2024
// Works with renderFromFile too
await ecto.renderFromFile('./template.hbs', { name: 'world', date: '2024-01-15' });
`$3
You can customize multiple engines in the same Ecto instance:
typescript
import { Ecto } from 'ecto';const ecto = new Ecto();
// Customize Handlebars with helpers
ecto.handlebars.engine.registerHelper('bold', (text) => {
return
${text};
});// Customize EJS options
ecto.ejs.opts = {
...ecto.ejs.opts,
delimiter: '?',
openDelimiter: '[',
closeDelimiter: ']'
};
// Customize Markdown options
ecto.markdown.opts = {
...ecto.markdown.opts,
html: true,
breaks: true
};
// Use all customized engines
await ecto.render('{{bold "Hello"}}', {}, 'handlebars');
await ecto.render('[? name ?]', { name: 'World' }, 'ejs');
await ecto.render('# Hello\n\nVisit https://example.com', {}, 'markdown');
`$3
You can configure Handlebars to look for partials in multiple directories:
typescript
import { Ecto } from 'ecto';const ecto = new Ecto();
// Configure where to look for partials
ecto.handlebars.partialsPath = ['partials', 'includes', 'components', 'layouts'];
ecto.handlebars.rootTemplatePath = './templates';
// Now partials will be loaded from multiple directories
await ecto.render('{{> header}}Content{{> footer}}', {}, 'handlebars');
`$3
You can also use the exported engine classes independently of Ecto:
typescript
import { Handlebars } from 'ecto';// Create a standalone engine instance
const handlebars = new Handlebars();
// Add custom helpers
handlebars.engine.registerHelper('shout', (text) => {
return text.toUpperCase() + '!!!';
});
// Use it directly
const result = await handlebars.render('{{shout greeting}}', { greeting: 'hello' });
console.log(result); // HELLO!!!
`This pattern is particularly powerful when:
- You need consistent helpers across all templates
- You want to configure engine-specific options globally
- You're building a framework or application with specific template requirements
- You need to extend engine functionality beyond default behavior
Creating a Custom Engine
To create a custom engine, you need to:
1. Extend the
class
2. Implement the EngineInterface
3. Define your engine's name and file extensions
4. Implement the and renderSync methods$3
Here's a simple example of a custom uppercase engine:
`typescript
import { BaseEngine, type EngineInterface } from 'ecto';class UppercaseEngine extends BaseEngine implements EngineInterface {
constructor(options?: Record) {
super();
// Define the engine name(s)
this.names = ['uppercase', 'upper'];
// Set any options
this.opts = options;
// Define file extensions this engine handles
this.setExtensions(['upper', 'uppercase']);
}
async render(source: string, data?: Record): Promise {
// Simple rendering logic: replace variables and uppercase everything
let result = source;
if (data) {
// Replace {{variable}} with data values
for (const [key, value] of Object.entries(data)) {
const regex = new RegExp(
\\{\\{\\s${key}\\s\\}\\}, 'g');
result = result.replace(regex, String(value));
}
} // Convert to uppercase
return result.toUpperCase();
}
renderSync(source: string, data?: Record): string {
// Same logic for synchronous rendering
let result = source;
if (data) {
for (const [key, value] of Object.entries(data)) {
const regex = new RegExp(
\\{\\{\\s${key}\\s\\}\\}, 'g');
result = result.replace(regex, String(value));
}
} return result.toUpperCase();
}
}
// Use the custom engine
const engine = new UppercaseEngine();
const result = await engine.render('Hello {{name}}!', { name: 'World' });
console.log(result); // Output: HELLO WORLD!
`$3
To use your custom engine with the main Ecto class, you need to register it:
typescript
import { Ecto } from 'ecto';const ecto = new Ecto();
// Create and register your custom engine
const uppercaseEngine = new UppercaseEngine();
// Add to the engines collection
ecto.engines.set('uppercase', uppercaseEngine);
// Register the file extensions
ecto.mappings.set('uppercase', ['upper', 'uppercase']);
// Now you can use it with render
const result = await ecto.render('Hello {{name}}!', { name: 'World' }, 'uppercase');
console.log(result); // HELLO WORLD!
// Or with renderFromFile (for .upper or .uppercase files)
await ecto.renderFromFile('./template.upper', { name: 'World' });
`$3
Here's a more advanced example that wraps an external template library:
typescript
import { BaseEngine, type EngineInterface } from 'ecto';
import Handlebars from 'handlebars'; // Example external libraryclass CustomHandlebarsEngine extends BaseEngine implements EngineInterface {
constructor(options?: Record) {
super();
this.names = ['custom-handlebars'];
this.opts = options;
this.setExtensions(['chbs']);
// Initialize the underlying engine
this.engine = Handlebars.create();
// Register custom helpers
this.engine.registerHelper('shout', (text: string) => {
return text.toUpperCase() + '!!!';
});
this.engine.registerHelper('whisper', (text: string) => {
return text.toLowerCase() + '...';
});
}
async render(source: string, data?: Record): Promise {
const template = this.engine.compile(source, this.opts);
return template(data);
}
renderSync(source: string, data?: Record): string {
const template = this.engine.compile(source, this.opts);
return template(data);
}
}
// Usage
const engine = new CustomHandlebarsEngine();
const result = await engine.render(
'Normal: {{name}}, Shout: {{shout name}}, Whisper: {{whisper name}}',
{ name: 'Hello' }
);
console.log(result);
// Output: Normal: Hello, Shout: HELLO!!!, Whisper: hello...
`$3
If your engine needs to support partials, you can handle the
:`typescript
import fs from 'node:fs';
import { BaseEngine, type EngineInterface } from 'ecto';class CustomEngineWithPartials extends BaseEngine implements EngineInterface {
private partials: Map = new Map();
constructor(options?: Record) {
super();
this.names = ['custom-partials'];
this.opts = options;
this.setExtensions(['cpart']);
}
async render(source: string, data?: Record): Promise {
// Load partials if rootTemplatePath is set
if (this.rootTemplatePath) {
await this.loadPartials(this.rootTemplatePath);
}
// Process includes: {{> partialName}}
let result = source;
const includeRegex = /\{\{>\s(\w+)\s\}\}/g;
result = result.replace(includeRegex, (match, partialName) => {
return this.partials.get(partialName) || match;
});
// Process variables: {{variableName}}
if (data) {
for (const [key, value] of Object.entries(data)) {
const regex = new RegExp(
\\{\\{\\s${key}\\s\\}\\}, 'g');
result = result.replace(regex, String(value));
}
} return result;
}
renderSync(source: string, data?: Record): string {
if (this.rootTemplatePath) {
this.loadPartialsSync(this.rootTemplatePath);
}
let result = source;
const includeRegex = /\{\{>\s(\w+)\s\}\}/g;
result = result.replace(includeRegex, (match, partialName) => {
return this.partials.get(partialName) || match;
});
if (data) {
for (const [key, value] of Object.entries(data)) {
const regex = new RegExp(
\\{\\{\\s${key}\\s\\}\\}, 'g');
result = result.replace(regex, String(value));
}
} return result;
}
private async loadPartials(partialsPath: string): Promise {
const files = await fs.promises.readdir(partialsPath);
for (const file of files) {
if (file.endsWith('.cpart')) {
const name = file.replace('.cpart', '');
const content = await fs.promises.readFile(
${partialsPath}/${file},
'utf-8'
);
this.partials.set(name, content);
}
}
} private loadPartialsSync(partialsPath: string): void {
const files = fs.readdirSync(partialsPath);
for (const file of files) {
if (file.endsWith('.cpart')) {
const name = file.replace('.cpart', '');
const content = fs.readFileSync(
${partialsPath}/${file}, 'utf-8');
this.partials.set(name, content);
}
}
}
}// Usage
const engine = new CustomEngineWithPartials();
engine.rootTemplatePath = './templates/partials';
const result = await engine.render('{{> header}}\nHello {{name}}!\n{{> footer}}', {
name: 'World'
});
`Engine Interface Reference
When creating a custom engine, implement these required methods:
typescript
interface EngineInterface {
// Engine name(s) - can support multiple aliases
names: string[]; // The underlying template engine (if wrapping a library)
engine: any;
// Optional configuration
opts?: Record;
// Root path for templates (used for partials/includes)
rootTemplatePath?: string;
// Async rendering method
render(source: string, data?: Record): Promise;
// Synchronous rendering method
renderSync(source: string, data?: Record): string;
}
`BaseEngine Helper Methods
The
class provides useful helper methods:-
getExtensions(): Get registered file extensions
- setExtensions(extensions: string[]): Set file extensions this engine handles
- deleteExtension(name: string)`: Remove a file extension1. Error Handling: Always wrap your rendering logic in try-catch blocks
2. Options: Make your engine configurable through the constructor options
3. Performance: Consider caching compiled templates if applicable
4. Type Safety: Use TypeScript for better development experience
5. Testing: Write comprehensive tests for your custom engine
6. Documentation: Document your engine's syntax and features
To contribute please ready our CONTRIBUTING.md guide. Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.