Cropper.js is a powerful javascript image cropper with cross-browser support and much more features. Also there is a jQuery plugin wrapper for Cropper.js
Croppie is a fast, easy to use jQuery image cropping plugin with many configuration options.
Smartcrop.js is a javascript library implementing content aware image cropping. Smartcrop.js implements an algorithm to find good crops for images.
A tutorial about how to resize and crop images using JavaScript and the HTML5 Canvas element using controls, commonly seen in photo editing applications.