rul

```js // 回溯 function fn(list, value) { let res = [] function helper(list, node) { if (node.id === value) { res = [...list] return } if (!node.children || !node.children.length) {...

```js Promise.retry = function(fn, times) { let n = 0 return new Promise((resolve, reject) => { next(resolve, reject) }) function next(resolve, reject) { fn().then(resolve).catch(e => { n++ n === times...

```js function flatten(arr) { if (!arr.length) { return [] } let stack = [...arr] let res = [] while (stack.length) { let item = stack.pop() if (Array.isArray(item)) { for (let...

```js function multiRequest(urls, maxNum) { let len = urls.length, max = Math.min(len, maxNum), res = [] let start = 0, end = 0 return new Promise(resolve => { for (let...

```js function normalize(str) { let len = str.length, stack = [], j = 0 for (let i = 0; i < len; i++) { if (str[i] === '[') { j++...

```js function reduction(arr) { let res = [] while (arr.length) { if (res.length) { res.push(res.shift()) } res.push(arr.pop()) } return res } reduction([1, 2, 3, 4, 5, 6, 7, 8, 9,...

```js function trans(obj) { let res = {} let temp for (let key in obj) { temp = res let arr = key.split('.') let len = arr.length for (let i...

```js function getRandomK(n, k) { let arr = Array.from({ length: n }).map((v, i) => i) for (let i = n - 1; i >= n - k; i--) { let...