ES5 bind

[Raynos]

bound = function () {
    return self.apply( nop.prototype && this instanceof nop ? this : ( obj || {} ),
        args.concat( slice.call(arguments) ) );
};

https://es5.github.com/#x15.3.4.5

Set the [[Construct]] internal property of F as described in 15.3.4.5.2.

https://es5.github.com/#x15.3.4.5.2

Return the result of calling the [[Construct]] internal method oftarget providing args as the arguments.

https://es5.github.com/#x13.2.2

Return obj.

Basically your code always returns the return value of the bound function and doesn't handle cases like

new ( (function () {
  return undefined;
}).bind(lulz, args) ) !== undefined;

Here the return value of invoking new (and [[Construct]]) on the bound function should be that the new instance is returned, not the return value of the bound function.

Again see es5-shim for implementation.

[olivernn]

Included in the latest version