Function.prototype.then

then.js

    function square(x) {
        return x*x;
    }

    function add3(x) {
        return x + 3;
    }

    function sub10(x) {
        return x - 10;
    }



    Function.prototype.then = function(func) {

        var that = this;

        return function() {
            return func(that.apply(null, arguments));
        }
    }

    square.then(add3).then(sub10)(10); // -> 9993