modernizr/src/fnBind.js

Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser.

define(['slice'], function( slice ) {
  // Adapted from ES5-shim https://github.com/kriskowal/es5-shim/blob/master/es5-shim.js
  // es5.github.com/#x15.3.4.5

  if (!Function.prototype.bind) {
    Function.prototype.bind = function bind(that) {

      var target = this;

      if (typeof target != "function") {
        throw new TypeError();
      }

      var args = slice.call(arguments, 1);
      var bound = function() {

        if (this instanceof bound) {

          var F = function(){};
          F.prototype = target.prototype;
          var self = new F();

          var result = target.apply(
            self,
            args.concat(slice.call(arguments))
          );
          if (Object(result) === result) {
            return result;
          }
          return self;

        } else {

          return target.apply(
            that,
            args.concat(slice.call(arguments))
          );

        }

      };

      return bound;
    };
  }

  return Function.prototype.bind;
});