数组处理，矩阵转置

想取出数组中第I个值重新组合成数组 

<script>
    var deepArr=[
        [1,2,3,4],
        [1,2,3,4],
        [1,2,3,4],
    ];

    // var deepArr=[
    //     [1,1,1],
    //     [2,2,2],
    //     [3,3,3],
    //     [4,4,4],
    // ];
    function reverseMatrix(sourceArr) {
        var reversedArr = [];
        for (var n = 0; n < sourceArr[0].length; n++) {
            reversedArr[n] = [];
            for (var j = 0; j < sourceArr.length; j++) {
                reversedArr[n][j] = sourceArr[j][n];
            }
        }
        return reversedArr;
    }

    console.log(reverseMatrix(deepArr));
</script>