【JS数据算法】数组扁平化

基于flat

// flat是专门用于数组扁平化的方法
//  + 可传入参数为number类型
//  + 数字为扁平化的层数
//  + Infinity为扁平化所有数组
let arr = [1, 2, [3, 4, [5, 6, [7, [8, [9], 10], 11, 12], 13, 14, 15], 16], 17];
console.log(arr.flat(Infinity)) // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]

基于字符串

// toString
let arr = [1, 2, [3, 4, [5, 6, [7, [8, [9], 10], 11, 12], 13, 14, 15], 16], 17],
	str = arr.toString().split(',');
arr = str.map(item => parseInt(item));
console.log(arr) // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]

// 或者
// JSON.stringify
let arr = [1, 2, [3, 4, [5, 6, [7, [8, [9], 10], 11, 12], 13, 14, 15], 16], 17],
    str = JSON.stringify(arr).replace(/(\[|\])/g, '').split(',');
arr = str.map(item => parseInt(item))
console.log(arr) // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]

基于concat

// 循环数组中每一项
// 如果当前项为数组则扁平化当前项
let arr = [1, 2, [3, 4, [5, 6, [7, [8, [9], 10], 11, 12], 13, 14, 15], 16], 17],
    i = 0;

for (; i < arr.length - 1; i++) {
    if (Array.isArray(arr[i])) {
        arr = [].concat(...arr)
    }
}
console.log(arr) // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]

递归算法

let arr = [1, 2, [3, 4, [5, 6, [7, [8, [9], 10], 11, 12], 13, 14, 15], 16], 17],
    result = [];
function myFlat(arr) {
    let i = 0;
    for (; i < arr.length; i++) {
        if (Array.isArray(arr[i])) {
            myFlat(arr[i]);
            continue;
        }
        result.push(arr[i])
    }
    return result
}
console.log(myFlat(arr))