in_the_beginning_there_was_foreach.js

// Array methods as variations of forEach
({
    forEach: function (fn) {    
        var i;
        for (i = 0; i < this.length; i++) {
            fn(this[i], i, this);
        }
    },

    map: function (fn) {
        var result = [];
        this.forEach(function () {
            result.push(fn.apply(this, arguments));
        });
        return result;
    },

    every: function (fn) {
        var result = true;
        this.forEach(function () {
            result &= fn.apply(this, arguments);
        });
        return result;
    }
})