给定一个二维数组（矩阵），如何使用JavaScript进行矩阵的转置？
方法1：
● 将二维数组存储到变量中。
● 显示二维数组(矩阵)内容。
● 调用map()方法，它为数组中的每个元素提供一次回调函数，相对于数组对角线调换数组中元素的位置。
示例：使用array.map()方法
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body style = "text-align:center;">
<p id = "Array" style = "font-size: 16px; font-family: sans-serif; font-weight: bold;"></p>
<button onclick = "Run()"> 点击这里</button>
<p id = "Array_DOWN" style = "color:green; font-size: 20px; font-weight: bold;"></p>
<script>
var el_up = document.getElementById("Array");
var el_down = document.getElementById("Array_DOWN");
var array = [
[1, 1, 1],
[2, 2, 2],
[3, 3, 3],
];
el_up.innerHTML = "[ [ " + array[0] + " ] ], [ [ "
+ array[1] + " ] ], [ [ " + array[2] + " ] ]";
function transpose(mat) {
for (var i = 0; i < mat.length; i++) {
for (var j = 0; j < i; j++) {
const tmp = mat[i][j];
mat[i][j] = mat[j][i];
mat[j][i] = tmp;
}
}
}
function Run() {
array = array[0].map((col, i) => array.map(row => row[i]));
el_down.innerHTML = "[ [ " + array[0] + " ] ], [ [ "
+ array[1] + " ] ], [ [ " + array[2] + " ] ]";
}
</script>
</body>
</html>方法2：
● 将二维数组存储到变量中。
● 将数组中的每个元素替换为其相对于数组对角线的镜像。
示例：创建一个函数，该函数用镜像替换每个元素以获取数组的转置。
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body style = "text-align:center;">
<p id = "Array" style = "font-size: 16px; font-family: sans-serif; font-weight: bold;"></p>
<button onclick = "gfg_Run()"> 点击这里</button>
<p id = "Array_DOWN" style = "color:red; font-size: 20px; font-weight: bold;"></p>
<script>
var el_up = document.getElementById("Array");
var el_down = document.getElementById("Array_DOWN");
var array = [
[1, 1, 1],
[2, 2, 2],
[3, 3, 3],
];
el_up.innerHTML = "[ [ " + array[0] + " ] ], [ [ "
+ array[1] + " ] ], [ [ " + array[2] + " ] ]";
function transpose(mat) {
for (var i = 0; i < mat.length; i++) {
for (var j = 0; j < i; j++) {
const tmp = mat[i][j];
mat[i][j] = mat[j][i];
mat[j][i] = tmp;
}
}
}
function gfg_Run() {
transpose(array);
el_down.innerHTML = "[ [ " + array[0] + " ] ], [ [ "
+ array[1] + " ] ], [ [ " + array[2] + " ] ]";
}
</script>
</body>
</html> 
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