JavaScript implements

array.js

// https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array

/*
 * Implemented in JavaScript 1.6
 */
Array.prototype.forEach = Array.prototype.forEach || function(fun /*, thisp*/) {
    var len = this.length >>> 0;
    if(typeof fun != 'function') { throw new TypeError(fun + ' is not a function'); }
    for(var thisp = arguments[1], i = 0; i < len; i++) {
        if(i in this) {
            fun.call(thisp, this[i], i, this);
        }
    }
};

/*
 * Implemented in JavaScript 1.6
 */
Array.prototype.indexOf = Array.prototype.indexOf || function(elt /*, from*/) {
    var len = this.length >>> 0,
    from = Number(arguments[1]) || 0;
    if(from < 0) {
        from += len;
    }
    for(; from < len; from++) {
        if(from in this && this[from] === elt) {
            return from;
        }
    }
    return -1;
};

/*
 * Implemented in JavaScript 1.6
 */
Array.prototype.filter = Array.prototype.filter || function(fun /*, thisp*/) {
    var len = this.length >>> 0;
    if(typeof fun != 'function') { throw new TypeError(fun + ' is not a function'); }
    var res = [], thisp = arguments[1];
    for(var i = 0, val; i < len; i++) {
        if(i in this) {
            val = this[i];
            fun.call(thisp, this[i], i, this) && res.push(val);
        }
    }
    return res;
};