【前端_js】javascript中數組的map()方法

數組的map()方法用於遍歷數組，每遍歷一個元素就調用回調方法一次，並將回調函數的返回結果作為新數組的元素，被遍歷的數組不會被改變。

語法：let newAarray = arr.map(function callback(currentValue, index, array) { // Return element for newArray }

示例：

let numbers = [1, 5, 10, 15];
let doubles = numbers.map((x) => {
   return x * 2;
});

// doubles is now [2, 10, 20, 30]
// numbers is still [1, 5, 10, 15]


let numbers = [1, 4, 9];
let roots = numbers.map(Math.sqrt);

// roots is now [1, 2, 3]
// numbers is still [1, 4, 9]

參考博文：javascript map()方法解析