If your browser does not support ECMAScript 5 .bind() method.

bind.js

if (!Function.prototype.bind) {
    Function.prototype.bind = function(oThis) {
        if (typeof this != 'function') {
            // closest thing possible to the ECMAScript 5 internal IsCallable function
            throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
        }

        var
            aArgs = Array.prototype.slice.call(arguments, 1),
            f2Bind = this,
            fNOP = function() {},
            fBound = function() {
                return f2Bind.apply(this instanceof fNOP && oThis ? this : oThis, aArgs.concat(Array.prototype.slice.call(arguments)));
            };

        fNOP.prototype = this.prototype;
        fBound.prototype = new fNOP();

        return fBound;
    };
}