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function range(start, end, step) {

    if (arguments.length === 0) {
        throw new Error('range fuction expect at least 1 argument')
    }

    if (arguments.length === 1) {
        end = start
        start = 0
        step = 1

hjzheng

function genArray(rows, cols, something) {
  // BAD! Rows are copied by reference
  // return new Array(rows).fill(new Array(cols).fill(something))
  
  // good way
  Array.from(Array(rows), () => new Array(cols).fill(something))
  
  // more inefficient 12%
  // return new Array(rows).fill(null).map(() => Array(cols).fill(something))
}

hjzheng

HTML和CSS基础

1. 熟悉 VS Code，注意几个常用插件的配置
2. 熟悉 html 页面结构 ( 强调 doctype ), 注意 html规范
3. 使用 Chrome dev tools 调试 CSS, HTML
4. 使用 jsbin.com 写自己的 demo 页面
5. reset.css 例如 normalize.css (为什么会有rest.css 和 浏览器的差异性)
6. 盒模型
7. CSS Layout 一些知识 传送门

• block, inline 和 inline-block 元素特点

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1.递归

function recur(level, params...) {
  // 终止条件
  if (level < maxLevel) {
    process_result
    return
  }
  
 // 处理当前层

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function generatePassword(length) {

    let charsets = ['ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz', '0123456789', '!#$%&*']

    let allCharsets = charsets.join('')

    let retVal = ''

    for (let i = 0, len = charsets.length; i < len; i++) {
        let n = charsets[i].length

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function base58(encodeMap) {
  function base58encode(int64: string): string {
    let num = BigInt(int64)
    const base = 58n

    let res = ''
    while (num >= base) {
      res += encodeMap[num % base]
      num = num / base
    }

hjzheng

目录

1. 什么是XSS
2. XSS原理
3. XSS危害
4. XSS攻击 （攻击分类与举例）
5. XSS防御
6. XSS检测

什么是 XSS

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// Sequence generator function (commonly referred to as "range", e.g. Clojure, PHP etc)
const range = (start, stop, step) => Array.from({ length: (stop - start) / step + 1}, (_, i) => start + (i * step));

// create 2d array
const create2DArray = (m, n, initVal) => Array.from(new Array(m), () => new Array(n).fill(initVal))

// create 3d array
const create3DArray = (m, n, d, initVal) => Array.from(new Array(m), () => Array.from(new Array(n), () => new Array(d).fill(initVal)))

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class PriorityQueue {
    constructor(data = [], compare = defaultCompare) {
        this.data = data
        this.length = this.data.length
        this.compare = compare

        if (this.length > 0) {
            for (let i = (this.length >> 1) - 1; i >= 0; i--) this._down(i)
        }
    }

hjzheng

前端导出 excel 说明

利用js-xlsx来导出excel,纯前端实现实现

参考: 如何使用JavaScript实现纯前端读取和导出excel文件