将基于其他数组值的数组填充到Javascript中所需的数字

let arr = new Array(5);
arr.fill(0); // [0, 0, 0, 0, 0]

let sourceArray = [1, 2, 3, 4];
let newArray = sourceArray.map(value => value * 2); // [2, 4, 6, 8]

let sourceArray = [1, 2, 3, 4];
let newArray = Array.from(sourceArray, value => value * 2); // [2, 4, 6, 8]

let arr = new Array(5);
for (let i = 0; i < arr.length; i++) {
    arr[i] = i * 2;
} // [0, 2, 4, 6, 8]

let sourceArray = [1, 2, 3, 4];
let newArray = sourceArray.map(value => {
    return value * 2; // 确保有返回值
}); // [2, 4, 6, 8]

let sourceArray = [1, null, 3, undefined, 5];
let newArray = sourceArray.map(value => {
    return value ? value * 2 : 0; // 如果值存在则乘以2，否则返回0
}); // [2, 0, 6, 0, 10]