为什么这段代码 操作原数组，会影响到复制的数组。

就是我对原数组排序，复制的数组也跟着排序了。

function validSolution(board){
    let result = {};
    // let copy = [];
    // let copy = board.slice(0);
    let copy = board.concat([]);
    // for(var i=0;i<board.length;i++){
    //     copy[i]=board[i];
    // }

    let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];

    for(let i = 0; i < board.length; i++) {
        if(board[i].sort(function (a,b) {
                return a-b;
            }).toString() == arr.toString()) {
            //经过排序后影响到复制数组
            for(let j = 0; j < 9; j++) {
                if(!result[j]) {
                    result[j] = [];
                }
                result[j].push(copy[i][j]);
            }
        }else {
            return false;
        }
    }

    for (let i in result) {
        if(result[i].sort((a,b) => a-b).toString() !== arr.toString()) return false;
    }

    return true;
}


console.log(validSolution([[5, 3, 4, 6, 7, 8, 9, 1, 2],
    [6, 7, 2, 1, 9, 5, 3, 4, 8],
    [1, 9, 8, 3, 4, 2, 5, 6, 7],
    [8, 5, 9, 7, 6, 1, 4, 2, 3],
    [4, 2, 6, 8, 5, 3, 7, 9, 1],
    [7, 1, 3, 9, 2, 4, 8, 5, 6],
    [9, 6, 1, 5, 3, 7, 2, 8, 4],
    [2, 8, 7, 4, 1, 9, 6, 3, 5],
    [3, 4, 5, 2, 8, 6, 1, 7, 9]]));

console.log(validSolution([[5, 3, 4, 6, 7, 8, 9, 1, 2],
    [6, 7, 2, 1, 9, 0, 3, 4, 8],
    [1, 0, 0, 3, 4, 2, 5, 6, 0],
    [8, 5, 9, 7, 6, 1, 0, 2, 0],
    [4, 2, 6, 8, 5, 3, 7, 9, 1],
    [7, 1, 3, 9, 2, 4, 8, 5, 6],
    [9, 0, 1, 5, 3, 7, 2, 1, 4],
    [2, 8, 7, 4, 1, 9, 6, 3, 5],
    [3, 0, 0, 4, 8, 1, 1, 7, 9]]));

---

因为是浅复制，board的每一项是一个数组，concat是进行浅复制，copy的每一项和board对应的每一项都指向相同的数组。。
你需要lodash

let copy =_.cloneDeep(board);