contentstack


JavaScript Content Delivery SDK for Contentstack

Contentstack is a headless CMS with an API-first approach. It is a CMS that developers can use to build powerful cross-platform applications in their favorite languages. Build your application frontend, and Contentstack will take care of the rest. Read More.

Contentstack provides JavaScript SDK to build application on top of JavaScript. Given below is the detailed guide and helpful resources to get started with our JavaScript SDK.

The JavaScript SDK can also be used to create Node.js and React native applications.

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You need Node.js version 4.4.7 or later installed to use the Contentstack JavaScript SDK.

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#### For JavaScript (Browser)
For browsers, we recommend to download the library via npm or yarn to ensure 100% availability.

If you'd like to use a standalone built file you can use the following script tag or download it from jsDelivr, under the dist directory:

``html

`
You can also specify a specific version number.
`html

`

To initialize the SDK, you will need to specify the API Key, Delivery Token, and Environment Name of your stack.

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment" });
`

For Setting the European Region:
If you want to set and use European region, refer to the code below:

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment", "region": Contentstack.Region.EU });
`

#### For Node.js

Node.js uses the Javascript SDK to create apps. To use the JavaScript SDK, install it via npm:

`bash
npm i contentstack
`

To import the SDK in your project, use the following command:

`javascript
import Contentstack from ‘contentstack’
`

To initialize the SDK, you will need to specify the API Key, Delivery Token, and Environment Name of your stack.

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment" });
`

For Setting the European Region:

If you want to set and use European region, refer to the code below:

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment", "region": Contentstack.Region.EU });
`

#### For React Native

React Native uses the Javascript SDK to create apps. To use the JavaScript SDK, install it via npm:

`bash
npm i contentstack
`

To import the SDK in your project, use the following command:

`javascript
import Contentstack from contentstack
`

To initialize the SDK, you will need to specify the API Key, Delivery Token, and Environment Name of your stack.

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment" });
`

For Setting the European Region:

If you want to set and use European region, refer to the code below:

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment" "region": Contentstack.Region.EU });
`

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#### Stack

A stack is like a container that holds the content of your app. Learn more about Stacks.

#### Content Type

Content type lets you define the structure or blueprint of a page or a section of your digital property. It is a form-like page that gives Content Managers an interface to input and upload content. Read more.

#### Entry

An entry is the actual piece of content created using one of the defined content types. Learn more about Entries.

#### Asset

Assets refer to all the media files (images, videos, PDFs, audio files, and so on) uploaded to Contentstack. These files can be used in multiple entries. Read more about Assets.

#### Environment

A publishing environment corresponds to one or more deployment servers or a content delivery destination where the entries need to be published. Learn how to work with Environments.

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#### Initializing your SDK

You will need to specify the API key, Delivery Token, and Environment Name of your stack to initialize the SDK:

`javascript
const Stack = Contentstack.Stack({ "api_key": "api_key", "delivery_token": "delivery_token", "environment": "environment" });
`

Once you have initialized the SDK, you can start getting content in your app.

#### Querying content from your stack

To get a single entry, you need to specify the content type as well as the ID of the entry.

`javascript
const Query = Stack.ContentType('blog').Entry("");

Query
.toJSON()
.fetch()
.then(function success(entry) {
console.log(entry.get('title')); // Retrieve field value by providing a field's uid
}, function error(err) {
// err object
})
`

To retrieve multiple entries of a content type, you need to specify the content type uid. You can also specify search parameters to filter results.

`javascript
const Query = Stack.ContentType('blog').Query();

Query
.where("title", "welcome")
.includeContentType()
.includeCount()
.toJSON()
.find()
.then(function success(result) {
// result is array where -
// result[0] => entry objects
// result[result.length-1] => entry objects count included only when .includeCount() is queried.
// result[1] => schema of the content type is included when .includeContentType() is queried.
}, function error(err) {
// err object
})
`

#### Cache Policies

You can set a cache policy on a stack and/or query object.

##### Setting a cache policy on a stack

This option allows you to globalize a cache policy. This means the cache policy you set will be applied to all the query objects of the stack.

`javascript
//Setting a cache policy on a stack
Stack.setCachePolicy(Contentstack.CachePolicy.NETWORK_ELSE_CACHE)
`

##### Setting a cache policy on a query object

This option allows you to set/override a cache policy on a specific query object.

`javascript
// setting a cache policy on a queryobject
Query.setCachePolicy(Contentstack.CachePolicy.CACHE_THEN_NETWORK)
`

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You can query for content types, entries, assets and more using our JavaScript API Reference.

JavaScript API Reference Doc

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We have introduced Image Delivery APIs that let you retrieve images and then manipulate and optimize them for your digital properties. It lets you perform a host of other actions such as crop, trim, resize, rotate, overlay, and so on.

For example, if you want to crop an image (with width as 300 and height as 400), you simply need to append query parameters at the end of the image URL, such as, https://images.contentstack.io/owl.jpg?crop=300,400. There are several more parameters that you can use for your images.

Read Image Delivery API documentation.

Following are Image Delivery API examples.

`javascript
// set the quality 100
imageUrl = Stack.imageTransform(imageUrl, {
'quality': 100
})

// set the quality to 100, auto optimization, width and height
imageUrl = Stack.imageTransform(imageUrl, {
'quality': 100,
'auto': 'webp',
'width': 100,
'height': 100
})
`

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The Sync API takes care of syncing your Contentstack data with your app and ensures that the data is always up-to-date by providing delta updates. Contentstack’s JavaScript SDK supports Sync API, which you can use to build powerful apps. Read through to understand how to use the Sync API with Contentstack JavaScript SDK.
Read Sync API documentation.

> Note: Sync function does not support cache policy. When using the Sync function, we recommend you to set the cache policy to IGNORE_CACHE.
##### Initial sync

The Initial Sync process performs a complete sync of your app data. It returns all the published entries and assets of the specified stack in response.

To start the Initial Sync process, use the syncStack method.

`javascript
let data = Stack.sync({"init": true})
data.then(function(sync_data, err) {
//error for any error description
//sync_data.items: contains sync data
//sync_data.paginationToken: for fetching the next batch of entries using pagination token
//sync_token.syncToken: for performing subsequent sync after initial sync
if (err) throw err
})
`
> Note: Sync function does not support cache policy. When using the Sync function, we recommend you to set the cache policy to IGNORE_CACHE.


The response also contains a sync token, which you need to store, since this token is used to get subsequent delta updates later, as shown in the Subsequent Sync section below.

You can also fetch custom results in initial sync by using advanced sync queries.

##### Sync pagination

If the result of the initial sync (or subsequent sync) contains more than 100 records, the response would be paginated. It provides pagination token in the response. You will need to use this token to get the next batch of data.

`javascript
let data = Stack.sync({"pagination_token" : ""})
data.then(function(result, err) {
//error for any error description
//result.items: contains sync data
//result.paginationToken: For fetching the next batch of entries using pagination token
//result.syncToken: For performing subsequent sync after initial sync
if(err) throw err
})
`

##### Subsequent sync

You can use the sync token (that you receive after initial sync) to get the updated content next time. The sync token fetches only the content that was added after your last sync, and the details of the content that was deleted or updated.

`javascript
let data = Stack.sync({"sync_token" : “”})
data.then(function(sync_data, err) {
//error for any error description
//sync_data.items: contains sync data
//sync_data.paginationToken: for fetching the next batch of entries using pagination token
//sync_token.syncToken: for performing subsequent sync after initial sync
if(err) throw err
})
``

##### Advanced sync queries

You can use advanced sync queries to fetch custom results while performing initial sync.
Read advanced sync queries documentation

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- Contentstack Website
- Official Documentation
- Content Delivery API Docs

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