extendscript-es5-shim/Array/forEach.js

a collection of useful es5-shims for Extendscript

/*
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
*/
// Production steps of ECMA-262, Edition 5, 15.4.4.18
// Reference: http://es5.github.io/#x15.4.4.18
if (!Array.prototype.forEach) {
    Array.prototype.forEach = function(callback, thisArg) {


        if (this === void 0 || this === null) {
            throw new TypeError('Array.prototype.forEach called on null or undefined');
        }

        // 1. Let O be the result of calling toObject() passing the
        // |this| value as the argument.
        var O = Object(this);

        // 2. Let lenValue be the result of calling the Get() internal
        // method of O with the argument "length".
        // 3. Let len be toUint32(lenValue).
        var len = O.length >>> 0;

        // 4. If isCallable(callback) is false, throw a TypeError exception. 
        // See: http://es5.github.com/#x9.11
        if (callback.__class__ !== 'Function') {
            throw new TypeError(callback + ' is not a function');
        }

        // 5. If thisArg was supplied, let T be thisArg; else let
        // T be undefined.
        var T = (arguments.length > 1) ? thisArg : void 0;


        // 6. Let k be 0
        //k = 0;

        // 7. Repeat, while k < len
        for (var k = 0; k < len; k++) {
            var kValue;
            // a. Let Pk be ToString(k).
            //    This is implicit for LHS operands of the in operator
            // b. Let kPresent be the result of calling the HasProperty
            //    internal method of O with argument Pk.
            //    This step can be combined with c
            // c. If kPresent is true, then
            if (k in O) {
                // i. Let kValue be the result of calling the Get internal
                // method of O with argument Pk.
                kValue = O[k];
                // ii. Call the Call internal method of callback with T as
                // the this value and argument list containing kValue, k, and O.
                callback.call(T, kValue, k, O);
            }
        }
        // 8. return undefined
    }
}