Image Resizing Client-Side with JavaScript Prior to Uploading

Resizing images client-side offers several advantages before their upload to the server. It reduces server load, speeds up page rendering, and provides a better user experience.

Is Client-Side JavaScript Image Resizing Possible?

Yes, it is possible to resize images client-side using JavaScript. There are open-source algorithms available that enable resizing without resorting to Flash.

Algorithm for Client-Side Image Resizing

One such algorithm is available on GitHub: https://gist.github.com/dcollien/312bce1270a5f511bf4a. It includes versions in both ES6 and vanilla JavaScript that can be embedded into any web application.

Example Usage

To use the algorithm:

1. Embed the provided JavaScript code into your web page.
2. Define an input for file selection and specify an image tag for displaying the resized image.
3. In the onchange event listener for the input, invoke the resize function provided by the algorithm. Specify the desired dimensions and a callback function.
4. The callback function will receive the resized blob and a flag indicating whether the resize was successful.
5. Use the returned blob to set the src attribute of the image tag for previewing the resized image.

Features

• Supports both ES6 and vanilla JavaScript.
• Automatically detects browser capabilities and applies polyfills for optimal compatibility.
• Ignores animated GIF images to maintain their integrity.