Compares two arrays for equality.
function _isEqualArray(a, b) {
        if (a === b) {
            return true;
        }
        if ((a === undefined) || (b === undefined)) {
            return false;
        }
        var i = a.length;
        if (i !== b.length){
            return false;
        }
        while (i--) {
            if (a[i] !== b[i]) {
                return false;
            }
        }
        return true;
    }