# Yahoo! UI Library

### yui 3.0.0b1

Yahoo! UI Library > yui > yui-array.js (source view)
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    /*
     * Provides information about the environment hosting YUI
     * @module yui
     * @submodule Array
     */

    (function() {

    var L = Y.Lang, Native = Array.prototype,

    /**
     * Adds the following array utilities to the YUI instance.  Additional
     * array helpers can be found in the collection component.
     * @class Array
     */

    /**
     * Y.Array(o) returns an array:
     * - Arrays are return unmodified unless the start position is specified.
     * - "Array-like" collections (@see Array.test) are converted to arrays
     * - For everything else, a new array is created with the input as the sole item
     * - The start position is used if the input is or is like an array to return
     *   a subset of the collection.
     *
     *   @TODO this will not automatically convert elements that are also collections
     *   such as forms and selects.  Passing true as the third param will
     *   force a conversion.
     *
     * @method ()
     * @static
     *   @param o the item to arrayify
     *   @param i {int} if an array or array-like, this is the start index
     *   @param al {boolean} if true, it forces the array-like fork.  This
     *   can be used to avoid multiple array.test calls.
     *   @return {Array} the resulting array
     */
    YArray = function(o, startIdx, al) {
        var t = (al) ? 2 : Y.Array.test(o), i, l, a;

        // switch (t) {
        //     case 1:
        //         // return (startIdx) ? o.slice(startIdx) : o;
        //     case 2:
        //         return Native.slice.call(o, startIdx || 0);
        //     default:
        //         return [o];
        // }

        if (t) {
            try {
                return Native.slice.call(o, startIdx || 0);
            // IE errors when trying to slice element collections
            } catch(e) {
                a=[];
                for (i=0, l=o.length; i<l; i=i+1) {
                    a.push(o[i]);
                }
                return a;
            }
        } else {
            return [o];
        }

    };

    Y.Array = YArray;

    /**
     * Evaluates the input to determine if it is an array, array-like, or
     * something else.  This is used to handle the arguments collection
     * available within functions, and HTMLElement collections
     *
     * @method test
     * @static
     *
     * @todo current implementation (intenionally) will not implicitly
     * handle html elements that are array-like (forms, selects, etc).
     *
     * @return {int} a number indicating the results:
     * 0: Not an array or an array-like collection
     * 1: A real array.
     * 2: array-like collection.
     */
    YArray.test = function(o) {
        var r = 0;
        if (L.isObject(o)) {
            if (L.isArray(o)) {
                r = 1;
            } else {
                try {
                    // indexed, but no tagName (element) or alert (window)
                    if ("length" in o && !("tagName" in o) && !("alert" in o) &&
                        (!Y.Lang.isFunction(o.size) || o.size() > 1)) {
                        r = 2;
                    }

                } catch(e) {}
            }
        }
        return r;
    };

    /**
     * Executes the supplied function on each item in the array.
     * @method each
     * @param a {Array} the array to iterate
     * @param f {Function} the function to execute on each item
     * @param o Optional context object
     * @static
     * @return {YUI} the YUI instance
     */
    YArray.each = (Native.forEach) ?
        function (a, f, o) {
            Native.forEach.call(a || [], f, o || Y);
            return Y;
        } :
        function (a, f, o) {
            var l = (a && a.length) || 0, i;
            for (i = 0; i < l; i=i+1) {
                f.call(o || Y, a[i], i, a);
            }
            return Y;
        };

    /**
     * Returns an object using the first array as keys, and
     * the second as values.  If the second array is not
     * provided the value is set to true for each.
     * @method hash
     * @static
     * @param k {Array} keyset
     * @param v {Array} optional valueset
     * @return {object} the hash
     */
    YArray.hash = function(k, v) {
        var o = {}, l = k.length, vl = v && v.length, i;
        for (i=0; i<l; i=i+1) {
            o[k[i]] = (vl && vl > i) ? v[i] : true;
        }

        return o;
    };

    /**
     * Returns the index of the first item in the array
     * that contains the specified value, -1 if the
     * value isn't found.
     * @method indexOf
     * @static
     * @param a {Array} the array to search
     * @param val the value to search for
     * @return {int} the index of the item that contains the value or -1
     */
    YArray.indexOf = (Native.indexOf) ?
        function(a, val) {
            return a.indexOf(val);
        } :
        function(a, val) {
            for (var i=0; i<a.length; i=i+1) {
                if (a[i] === val) {
                    return i;
                }
            }

            return -1;
        };

    /**
     * Numeric sort convenience function.
     * Y.ArrayAssert.itemsAreEqual([1, 2, 3], [3, 1, 2].sort(Y.Array.numericSort));
     * @method numericSort
     */
    YArray.numericSort = function(a, b) {
        return (a - b);
    };

    /**
     * Executes the supplied function on each item in the array.
     * Returning true from the processing function will stop the
     * processing of the remaining
     * items.
     * @method some
     * @param a {Array} the array to iterate
     * @param f {Function} the function to execute on each item
     * @param o Optional context object
     * @static
     * @return {boolean} true if the function returns true on
     * any of the items in the array
     */
     YArray.some = (Native.some) ?
        function (a, f, o) {
            return Native.some.call(a, f, o);
        } :
        function (a, f, o) {
            var l = a.length, i;
            for (i=0; i<l; i=i+1) {
                if (f.call(o, a[i], i, a)) {
                    return true;
                }
            }
            return false;
        };

    })();

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