bind模拟

if (!Function.prototype.bind) {

        Function.prototype.bind = function(oThis) {

        if (typeof this !== 'function') {

        throw new TypeError('What is trying to be bound is not callable');

    }

    var aArgs = Array.prototype.slice.call(arguments, 1),

        fToBind = this,

        fNOP = function() {},

        fBound = function() {

        return fToBind.apply(this.instanceof fNOP ? this : oThis,     aArgs.concat(Array.prototype.slice.call(arguments)));

        fNOP.prototype = this.prototype;

        fBound.prototype = new fNOP();

        return fBound;

        }

    }

}