shuffle(array) { //打乱数组
    var len = array.length;
    for(var i = 0; i < len; i++) {
        var end = len - 1;
        var index = (Math.random() * (end + 1)) >> 0;
        var t = array[end];
        array[end] = array[index];
        array[index] = t;
    }
    return array;
}