joecritch / imagekit-javascript

Javascript SDK for using ImageKit.io

ImageKit.io Javascript SDK

Javascript SDK for ImageKit.io that implements the client-side upload and URL generation for use in the browser.

ImageKit is a complete image optimization and transformation solution that comes with an image CDN and media storage. It can be integrated with your existing infrastructure - storage like AWS S3, web servers, your CDN, and custom domain names, allowing you to deliver optimized images in minutes with minimal code changes.

This SDK has no dependency.

Installation

Download the imagekit.js file from the dist directory or using the following command. Use the optional --save parameter if you wish to save the dependency in your package.json file.

npm install imagekit-javascript

Load it using a <script> tag.

<script type="text/javascript" src="imagekit.js"></script>

Initialization

var imagekit = new ImageKit({
    publicKey : "your_public_api_key",
    urlEndpoint : "https://ik.imagekit.io/your_imagekit_id",
    authenticationEndpoint : "http://www.yourserver.com/auth",
});    

publicKey and urlEndpoint are mandatory parameters for SDK initialization. authenticationEndpoint is essential if you want to use the SDK for client-side uploads.

Note: Do not include your Private Key in any client-side code, including this SDK or its initialization. If you pass the privateKey parameter while initializing this SDK, it throws an error

Usage

You can use this SDK for URL generation and client-side file uploads.

URL Generation

1. Using image path and image hostname or endpoint

This method allows you to create a URL using the path where the image exists and the URL endpoint (urlEndpoint) you want to use to access the image. You can refer to the documentation here to read more about URL endpoints in ImageKit and the section about image origins to understand about paths with different kinds of origins.

var imageURL = imagekit.url({
    path : "/default-image.jpg",
    urlEndpoint : "https://ik.imagekit.io/your_imagekit_id/endpoint/",
    transformation : [{
        "height" : "300",
        "width" : "400"
    }]
});

This results in a URL like

https://ik.imagekit.io/your_imagekit_id/endpoint/tr:h-300,w-400/default-image.jpg

2. Using full image URL

This method allows you to add transformation parameters to an existing, complete URL that is already mapped to ImageKit using the src parameter. This method should be used if you have the complete URL mapped to ImageKit stored in your database.

var imageURL = imagekit.url({
    src : "https://ik.imagekit.io/your_imagekit_id/endpoint/default-image.jpg",
    transformation : [{
        "height" : "300",
        "width" : "400"
    }]
});

This results in a URL like

https://ik.imagekit.io/your_imagekit_id/endpoint/default-image.jpg?tr=h-300%2Cw-400

The .url() method accepts the following parameters

Option	Description
urlEndpoint	Optional. The base URL to be appended before the path of the image. If not specified, the URL Endpoint specified at the time of SDK initialization is used. For example, https://ik.imagekit.io/your_imagekit_id/endpoint/
path	Conditional. This is the path at which the image exists. For example, /path/to/image.jpg. Either the path or src parameter need to be specified for URL generation.
src	Conditional. This is the complete URL of an image already mapped to ImageKit. For example, https://ik.imagekit.io/your_imagekit_id/endpoint/path/to/image.jpg. Either the path or src parameter need to be specified for URL generation.
transformation	Optional. An array of objects specifying the transformation to be applied in the URL. The transformation name and the value should be specified as a key-value pair in the object. Different steps of a chained transformation can be specified as different objects of the array. The complete list of supported transformations in the SDK and some examples of using them are given later. If you use a transformation name that is not specified in the SDK, it gets applied as it is in the URL.
transformationPostion	Optional. The default value is path that places the transformation string as a path parameter in the URL. It can also be specified as query which adds the transformation string as the query parameter tr in the URL. If you use src parameter to create the URL, then the transformation string is always added as a query parameter.
queryParameters	Optional. These are the other query parameters that you want to add to the final URL. These can be any query parameters and not necessarily related to ImageKit. Especially useful if you want to add some versioning parameter to your URLs.

Examples of generating URLs

1. Chained Transformations as a query parameter

var imageURL = imagekit.url({
    path : "/default-image.jpg",
    urlEndpoint : "https://ik.imagekit.io/your_imagekit_id/endpoint/",
    transformation : [{
        "height" : "300",
        "width" : "400"
    }, {
        "rotation" : 90
    }],
    transformationPosition : "query"
});

https://ik.imagekit.io/your_imagekit_id/endpoint/default-image.jpg?tr=h-300%2Cw-400%3Art-90

2. Sharpening and contrast transforms and a progressive JPG image

There are some transforms like Sharpening that can be added to the URL with or without any other value. To use such transforms without specifying a value, specify the value as "-" in the transformation object. Otherwise, specify the value that you want to be added to this transformation.

var imageURL = imagekit.url({
    src : "https://ik.imagekit.io/your_imagekit_id/endpoint/default-image.jpg",
    transformation : [{
        "format" : "jpg",
        "progressive" : "true",
        "effectSharpen" : "-",
        "effectContrast" : "1"
    }]
});

//Note that because `src` parameter was used, the transformation string gets added as a query parameter `tr`
https://ik.imagekit.io/your_imagekit_id/endpoint/default-image.jpg?tr=f-jpg%2Cpr-true%2Ce-sharpen%2Ce-contrast-1

List of supported transformations

The complete list of transformations supported and their usage in ImageKit can be found here. The SDK gives a name to each transformation parameter, making the code simpler and readable. If a transformation is supported in ImageKit, but a name for it cannot be found in the table below, then use the transformation code from ImageKit docs as the name when using in the url function.

Supported Transformation Name	Translates to parameter
height	h
width	w
aspectRatio	ar
quality	q
crop	c
cropMode	cm
x	x
y	y
focus	fo
format	f
radius	r
background	bg
border	bo
rotation	rt
blur	bl
named	n
overlayImage	oi
overlayX	ox
overlayY	oy
overlayFocus	ofo
overlayHeight	oh
overlayWidth	ow
overlayText	ot
overlayTextFontSize	ots
overlayTextFontFamily	otf
overlayTextColor	otc
overlayAlpha	oa
overlayTextTypography	ott
overlayBackground	obg
overlayImageTrim	oit
progressive	pr
lossless	lo
trim	t
metadata	md
colorProfile	cp
defaultImage	di
dpr	dpr
effectSharpen	e-sharpen
effectUSM	e-usm
effectContrast	e-contrast
effectGray	e-grayscale
original	orig

File Upload

The SDK provides a simple interface using the .upload() method to upload files to the ImageKit Media Library. It accepts all the parameters supported by the ImageKit Upload API.

The upload() method requires file and the fileName parameter.

Also, make sure that you have specified authenticationEndpoint during SDK initialization. The SDK makes an HTTP GET request to this endpoint and expects a JSON response with three fields, i.e. signature, token, and expire.

Learn how to implement authenticationEndpoint on your server.

You can pass other parameters supported by the ImageKit upload API using the same parameter name as specified in the upload API documentation. For example, to specify tags for a file at the time of upload, use the tags parameter as specified in the documentation here.

Sample usage

<form action="#" onsubmit="upload()">
    <input type="file" id="file1" />
    <input type="submit" />
</form>
<script type="text/javascript" src="../dist/imagekit.js"></script>

<script>
    /* SDK initilization
     authenticationEndpoint should be implemented on your server. Learn more here - https://docs.imagekit.io/api-reference/upload-file-api/client-side-file-upload#how-to-implement-authenticationendpoint-endpoint
    */
    var imagekit = new ImageKit({
        publicKey : "your_public_api_key",
        urlEndpoint : "https://ik.imagekit.io/your_imagekit_id",
        authenticationEndpoint : "http://www.yourserver.com/auth"
    });
    
    // Upload function internally uses the ImageKit.io javascript SDK
    function upload(data) {
        var file = document.getElementById("file1");
        imagekit.upload({
            file : file.files[0],
            fileName : "abc1.jpg",
            tags : ["tag1"]
        }, function(err, result) {
            console.log(arguments);
            console.log(imagekit.url({
                src: result.url,
                transformation : [{ height: 300, width: 400}]
            }));
        })
    }
</script>

If the upload succeeds, err will be null, and the result will be the same as what is received from ImageKit's servers. If the upload fails, err will be the same as what is received from ImageKit's servers, and the result will be null.

Demo Application

The fastest way to get started is by running the demo application. You can run the code locally. The source code is in samples/sample-app.

To run it:

git clone https://github.com/imagekit-developer/imagekit-javascript.git

cd imagekit-javascript

Create a file .env in the directory samples/sample-app and fill in your PRIVATE_KEY, PUBLIC_KEY and URL_ENDPOINT from your imageKit dashboard. The just run:

yarn startSampleApp