fabric.js/src/util/lang_function.js

(function() {
  
  var slice = Array.prototype.slice,
      apply = Function.prototype.apply,
      dummy = function() { };
  
  if (!Function.prototype.bind) {
    /**
     * Cross-browser approximation of ES5 Function.prototype.bind (not fully spec conforming)
     * @see <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind">Function#bind on MDN</a>
     * @param {Object} thisArg Object to bind function to
     * @param {Any[]} [...] Values to pass to a bound function
     * @return {Function}
     */
     Function.prototype.bind = function(thisArg) {
       var fn = this, args = slice.call(arguments, 1), bound;
       if (args.length) {
         bound = function() { 
           return apply.call(fn, this instanceof dummy ? this : thisArg, args.concat(slice.call(arguments))); 
         };
       }
       else {
         bound = function() { 
           return apply.call(fn, this instanceof dummy ? this : thisArg, arguments);
         };
       }
       dummy.prototype = this.prototype;
       bound.prototype = new dummy;
       
       return bound;
     };
  }
  
})();