underscore-template-loader

underscore-template-loader
==========================

An Underscore.js and Lodash template loader for Webpack

$3

* 1.2: Support for Webpack 5 (thx @idudinov)
* 1.1: Support macros through query (thx @JimYan, @devlinjunker)
* 1.0: Loader now works with Webpack 4. Still a beta release.

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``bash
npm install underscore-template-loader
`

Make sure you have the underscore or lodash package installed.

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`javascript
module.exports = {
//...
module: {
loaders: [
{ test: /\.html$/, loader: "underscore-template-loader" }
]
},
};
`

#### Template engine

You can specify an engine to specify the library used when you call underscore methods inside the template if you don't want to rely on the global _ that is used by default.

`javascript
module.exports = {
//...

module: {
loaders: [
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
engine: 'lodash',
}
}
]
}
};
`

#### Loading templates

`html



Hello <%=name%>


`

`javascript
var compiled = require('./hello.html');
return compiled({name: "world"});
`

#### Prepending filename comment

When debugging a large single page app with the DevTools, it's often hard to find the template that contains a bug. With the following config a HTML comment is prepended to the template with the relative path in it (e.g. ).

`javascript
module.exports = {
//...

module: {
loaders: [
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
prependFilenameComment: __dirname,
}
}
]
}
};
`

#### Template settings

You can override the delimiters used to determine data to injected (HTML-escaped or not) or code to evaluate in the templates.

`javascript
module.exports = {
//...

module: {
loaders: [
//...
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
interpolate: '\\{\\[(.+?)\\]\\}',
evaluate: '\\{%([\\s\\S]+?)%\\}',
escape: '\\{\\{(.+?)\\}\\}'
}
}
]
}
};
`

#### Template imports

_.templateSettings.imports automatically includes variables or functions in your templates. This is useful when you have utility functions that you want to make available to all templates without explicitly passing them in every time the template is used.

`html



<%= greet(name) %>


`

`javascript
var _ = require('lodash');
// Imports must be defined before the template is required
_.templateSettings.imports = {
greet: function(name) {
return 'Hello, ' + name + '!';
},
};
var compiled = require('./hello.html');
return compiled({name: "world"});
`

This is enabled by default when lodash is the engine used, but can be explicitly toggled using withImports option.

`javascript
module.exports = {
//...

module: {
loaders: [
//...
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
withImports: true,
}
}
]
}
};
`

#### Images

In order to load images you must install either the file-loader or the url-loader package.

`javascript
module.exports = {
//...

module: {
loaders: [
{ test: /\.html$/, loader: "underscore-template-loader" },
{ test: /\.jpg$/, loader: "file-loader" },
{ test: /\.png$/, loader: "url-loader?mimetype=image/png" },
]
}
};
`

`html





`

Images with an absolute path are not translated unless a root option is defined

`html





`

In order to deactivate image processing define attributes as an empty array.

`javascript
module.exports = {
//...

module: {
loaders: [
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
attributes: []
}
}
]
}
};
`

You could also add which attributes need to be processed in the form of pairs tag:attribute.

`javascript
module.exports = {
//...

module: {
loaders: [
//...
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
attributes: ['img:src', 'x-img:src']
}
}
]
}
};
`

Dynamic attributes won't be afected by this behaviour by default.

`html


`

In order to append the root directory you'll need to specify the parseDynamicRoutes argument.

`javascript
module.exports = {
//...

module: {
loaders: [
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
root: "myapp",
parseDynamicRoutes: true
}
}
]
}
};
`

`html


`

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Macros allow additional features like including templates or inserting custom text in compiled templates.

#### The require macro

The require macro expects a path to a underscore template. The macro is then translated into a webpack require expression that evaluates the template using the same arguments.

`html


Profile

Name: <%=name%>


Surname: <%=surname%>



`

This macro also supports an object literal as an additional argument.

`html



`

#### The include macro

While the require macro expects a resource that returns a function, the include macro can be used for resources that return plain text. For example, we can include text loaded through the html-loader directly in our template.

`html



`

#### br and nl

The br and nl macros insert a
tag and a new line respectively. They accept a optional argument with the amount of strings to insert.

`html


Lorem ipsum

@br(3)

Sit amet

@nl()
`

#### Custom macros

We can include additional macros by defining them in the webpack configuration file. Remember that the value returned by a macro is inserted as plain javascript, so in order to insert a custom text we need to use nested quotes. For example, let's say that we want a macro that includes a copyright string in our template.

`javascript
// File: webpack.config.js
const webpack = require('webpack');

module.exports = {
// ...

module: {
loaders: {
// ...
{ test: /\.html$/, loader: "underscore-template-loader" },
}
},

plugins: [
// ...
new webpack.LoaderOptionsPlugin({
options: {
macros: {
copyright: function () {
return "'

Copyright FakeCorp 2014 - 2018

'";
},
},
},
}),
],
}
`

We then invoke this macro from within the template as usual.

`html



`

#### Disabling macros

You can disable macros if you are a bit unsure about their usage or just simply want faster processing. This is achieved by setting the parseMacros options to false.

`javascript
module.exports = {
// ...

module: {
loaders: {
// ...
{
test: /\.html$/,
loader: "underscore-template-loader",
query: {
parseMacros: false
}
},
}
}
}
`

#### Arguments

Macros can accept an arbitrary number of arguments of different types: boolean, strings, numbers an object literals are supported.

`javascript
// File: webpack.config.js
module.exports = {
// ...

module: {
loaders: {
// ...
{ test: /\.html$/, loader: "underscore-template-loader" },
}
},

macros: {
header: function (size, content) {
return "'" + content + "'";
}
}
}
`

`html
@header(1, 'Welcome')


Lorem ipsum

@header(3, 'Contents')

Sit amet

`

#### Escaping

Macro expressions can be escaped with the \ character.

`html
@br(3)
\@nl()
@br()
`

Translates to

`html




@nl()


`

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`javascript
<%
const title = 'Some ' + 'title';
const headFileName = htmlWebpackPlugin.options.headFileName || 'head.ejs';

function objExtend(args, obj) {
args = Array.prototype.slice.call(args);
args[0] = Object.assign(obj, args[0]);
return args;
};
%>

<%= require(./structure/${headFileName}).apply(null, objExtend(arguments, { title })) %>
``

#### Known issues

* Trying to use different template settings (interpolate, escape, evaluate) for different extensions. Underscore / Lodash template settings are defined globally.

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Released under the MIT license.