#

API Docs for: 3.10.3
Show: Inherited Protected Private Deprecated

# File: collection/js/array-extras.js

    /**
    Adds additional utility methods to the `Y.Array` class.

    @module collection
    @submodule array-extras
    **/

    var A          = Y.Array,
        L          = Y.Lang,
        ArrayProto = Array.prototype;

    /**
    Returns the index of the last item in the array that contains the specified
    value, or `-1` if the value isn't found.

    @method lastIndexOf
    @param {Array} a Array to search in.
    @param {Any} val Value to search for.
    @param {Number} [fromIndex] Index at which to start searching backwards.
      Defaults to the array's length - 1. If negative, it will be taken as an offset
      from the end of the array. If the calculated index is less than 0, the array
      will not be searched and `-1` will be returned.
    @return {Number} Index of the item that contains the value, or `-1` if not
      found.
    @static
    @for Array
    **/
    A.lastIndexOf = L._isNative(ArrayProto.lastIndexOf) ?
        function(a, val, fromIndex) {
            // An undefined fromIndex is still considered a value by some (all?)
            // native implementations, so we can't pass it unless it's actually
            // specified.
            return fromIndex || fromIndex === 0 ? a.lastIndexOf(val, fromIndex) :
                    a.lastIndexOf(val);
        } :
        function(a, val, fromIndex) {
            var len = a.length,
                i   = len - 1;

            if (fromIndex || fromIndex === 0) {
                i = Math.min(fromIndex < 0 ? len + fromIndex : fromIndex, len);
            }

            if (i > -1 && len > 0) {
                for (; i > -1; --i) {
                    if (i in a && a[i] === val) {
                        return i;
                    }
                }
            }

            return -1;
        };

    /**
    Returns a copy of the input array with duplicate items removed.

    Note: If the input array only contains strings, the `Y.Array.dedupe()` method is
    a much faster alternative.

    @method unique
    @param {Array} array Array to dedupe.
    @param {Function} [testFn] Custom function to use to test the equality of two
        values. A truthy return value indicates that the values are equal. A falsy
        return value indicates that the values are not equal.

        @param {Any} testFn.a First value to compare.
        @param {Any} testFn.b Second value to compare.
        @param {Number} testFn.index Index of the current item in the original
            array.
        @param {Array} testFn.array The original array.
        @return {Boolean} _true_ if the items are equal, _false_ otherwise.

    @return {Array} Copy of the input array with duplicate items removed.
    @static
    **/
    A.unique = function (array, testFn) {
        var i       = 0,
            len     = array.length,
            results = [],
            j, result, resultLen, value;

        // Note the label here. It's used to jump out of the inner loop when a value
        // is not unique.
        outerLoop: for (; i < len; i++) {
            value = array[i];

            // For each value in the input array, iterate through the result array
            // and check for uniqueness against each result value.
            for (j = 0, resultLen = results.length; j < resultLen; j++) {
                result = results[j];

                // If the test function returns true or there's no test function and
                // the value equals the current result item, stop iterating over the
                // results and continue to the next value in the input array.
                if (testFn) {
                    if (testFn.call(array, value, result, i, array)) {
                        continue outerLoop;
                    }
                } else if (value === result) {
                    continue outerLoop;
                }
            }

            // If we get this far, that means the current value is not already in
            // the result array, so add it.
            results.push(value);
        }

        return results;
    };

    /**
    Executes the supplied function on each item in the array. Returns a new array
    containing the items for which the supplied function returned a truthy value.

    @method filter
    @param {Array} a Array to filter.
    @param {Function} f Function to execute on each item.
    @param {Object} [o] Optional context object.
    @return {Array} Array of items for which the supplied function returned a
      truthy value (empty if it never returned a truthy value).
    @static
    */
    A.filter = L._isNative(ArrayProto.filter) ?
        function(a, f, o) {
            return ArrayProto.filter.call(a, f, o);
        } :
        function(a, f, o) {
            var i       = 0,
                len     = a.length,
                results = [],
                item;

            for (; i < len; ++i) {
                if (i in a) {
                    item = a[i];

                    if (f.call(o, item, i, a)) {
                        results.push(item);
                    }
                }
            }

            return results;
        };

    /**
    The inverse of `Array.filter()`. Executes the supplied function on each item.
    Returns a new array containing the items for which the supplied function
    returned `false`.

    @method reject
    @param {Array} a the array to iterate.
    @param {Function} f the function to execute on each item.
    @param {object} [o] Optional context object.
    @return {Array} The items for which the supplied function returned `false`.
    @static
    */
    A.reject = function(a, f, o) {
        return A.filter(a, function(item, i, a) {
            return !f.call(o, item, i, a);
        });
    };

    /**
    Executes the supplied function on each item in the array. Iteration stops if the
    supplied function does not return a truthy value.

    @method every
    @param {Array} a the array to iterate.
    @param {Function} f the function to execute on each item.
    @param {Object} [o] Optional context object.
    @return {Boolean} `true` if every item in the array returns `true` from the
      supplied function, `false` otherwise.
    @static
    */
    A.every = L._isNative(ArrayProto.every) ?
        function(a, f, o) {
            return ArrayProto.every.call(a, f, o);
        } :
        function(a, f, o) {
            for (var i = 0, l = a.length; i < l; ++i) {
                if (i in a && !f.call(o, a[i], i, a)) {
                    return false;
                }
            }

            return true;
        };

    /**
    Executes the supplied function on each item in the array and returns a new array
    containing all the values returned by the supplied function.

    @example

        // Convert an array of numbers into an array of strings.
        Y.Array.map([1, 2, 3, 4], function (item) {
          return '' + item;
        });
        // => ['1', '2', '3', '4']

    @method map
    @param {Array} a the array to iterate.
    @param {Function} f the function to execute on each item.
    @param {object} [o] Optional context object.
    @return {Array} A new array containing the return value of the supplied function
      for each item in the original array.
    @static
    */
    A.map = L._isNative(ArrayProto.map) ?
        function(a, f, o) {
            return ArrayProto.map.call(a, f, o);
        } :
        function(a, f, o) {
            var i       = 0,
                len     = a.length,
                results = ArrayProto.concat.call(a);

            for (; i < len; ++i) {
                if (i in a) {
                    results[i] = f.call(o, a[i], i, a);
                }
            }

            return results;
        };

    /**
    Executes the supplied function on each item in the array, "folding" the array
    into a single value.

    @method reduce
    @param {Array} a Array to iterate.
    @param {Any} init Initial value to start with.
    @param {Function} f Function to execute on each item. This function should
      update and return the value of the computation. It will receive the following
      arguments:
        @param {Any} f.previousValue Value returned from the previous iteration,
          or the initial value if this is the first iteration.
        @param {Any} f.currentValue Value of the current item being iterated.
        @param {Number} f.index Index of the current item.
        @param {Array} f.array Array being iterated.
    @param {Object} [o] Optional context object.
    @return {Any} Final result from iteratively applying the given function to each
      element in the array.
    @static
    */
    A.reduce = L._isNative(ArrayProto.reduce) ?
        function(a, init, f, o) {
            // ES5 Array.reduce doesn't support a thisObject, so we need to
            // implement it manually.
            return ArrayProto.reduce.call(a, function(init, item, i, a) {
                return f.call(o, init, item, i, a);
            }, init);
        } :
        function(a, init, f, o) {
            var i      = 0,
                len    = a.length,
                result = init;

            for (; i < len; ++i) {
                if (i in a) {
                    result = f.call(o, result, a[i], i, a);
                }
            }

            return result;
        };

    /**
    Executes the supplied function on each item in the array, searching for the
    first item that matches the supplied function.

    @method find
    @param {Array} a the array to search.
    @param {Function} f the function to execute on each item. Iteration is stopped
      as soon as this function returns `true`.
    @param {Object} [o] Optional context object.
    @return {Object} the first item that the supplied function returns `true` for,
      or `null` if it never returns `true`.
    @static
    */
    A.find = function(a, f, o) {
        for (var i = 0, l = a.length; i < l; i++) {
            if (i in a && f.call(o, a[i], i, a)) {
                return a[i];
            }
        }
        return null;
    };

    /**
    Iterates over an array, returning a new array of all the elements that match the
    supplied regular expression.

    @method grep
    @param {Array} a Array to iterate over.
    @param {RegExp} pattern Regular expression to test against each item.
    @return {Array} All the items in the array that produce a match against the
      supplied regular expression. If no items match, an empty array is returned.
    @static
    */
    A.grep = function(a, pattern) {
        return A.filter(a, function(item, index) {
            return pattern.test(item);
        });
    };

    /**
    Partitions an array into two new arrays, one with the items for which the
    supplied function returns `true`, and one with the items for which the function
    returns `false`.

    @method partition
    @param {Array} a Array to iterate over.
    @param {Function} f Function to execute for each item in the array. It will
      receive the following arguments:
        @param {Any} f.item Current item.
        @param {Number} f.index Index of the current item.
        @param {Array} f.array The array being iterated.
    @param {Object} [o] Optional execution context.
    @return {Object} An object with two properties: `matches` and `rejects`. Each is
      an array containing the items that were selected or rejected by the test
      function (or an empty array if none).
    @static
    */
    A.partition = function(a, f, o) {
        var results = {
            matches: [],
            rejects: []
        };

        A.each(a, function(item, index) {
            var set = f.call(o, item, index, a) ? results.matches : results.rejects;
            set.push(item);
        });

        return results;
    };

    /**
    Creates an array of arrays by pairing the corresponding elements of two arrays
    together into a new array.

    @method zip
    @param {Array} a Array to iterate over.
    @param {Array} a2 Another array whose values will be paired with values of the
      first array.
    @return {Array} An array of arrays formed by pairing each element of the first
      array with an item in the second array having the corresponding index.
    @static
    */
    A.zip = function(a, a2) {
        var results = [];
        A.each(a, function(item, index) {
            results.push([item, a2[index]]);
        });
        return results;
    };

    /**
    Flattens an array of nested arrays at any abitrary depth into a single, flat
    array.

    @method flatten
    @param {Array} a Array with nested arrays to flatten.
    @return {Array} An array whose nested arrays have been flattened.
    @static
    @since 3.7.0
    **/
    A.flatten = function(a) {
        var result = [],
            i, len, val;

        // Always return an array.
        if (!a) {
            return result;
        }

        for (i = 0, len = a.length; i < len; ++i) {
            val = a[i];

            if (L.isArray(val)) {
                // Recusively flattens any nested arrays.
                result.push.apply(result, A.flatten(val));
            } else {
                result.push(val);
            }
        }

        return result;
    };