# 語言基礎
- 數據類型
```
<pre class="calibre14">```
undefined<span class="token2">,</span><span class="token5">null</span><span class="token2">,</span>boolean<span class="token2">,</span>number<span class="token2">,</span>string<span class="token2">,</span>Array基本數據類型
Object復雜數據類型
```
```
- 類型轉換
```
<pre class="calibre14">```
<span class="token1">parseInt</span><span class="token2">(</span><span class="token4">"666"</span> <span class="token2">)</span> 非數字返回NaN
<span class="token1">parseFloat</span><span class="token2">(</span><span class="token4">"2.45"</span><span class="token2">)</span><span class="token2">;</span>
<span class="token2">(</span><span class="token3">1</span><span class="token2">)</span><span class="token2">.</span><span class="token1">toString</span><span class="token2">(</span><span class="token2">)</span><span class="token2">;</span>
<span class="token2">(</span><span class="token3">10</span><span class="token2">)</span><span class="token2">.</span><span class="token1">toString</span><span class="token2">(</span><span class="token3">2</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//二進制</span>
<span class="token1">String</span><span class="token2">(</span>undefined<span class="token2">)</span><span class="token2">;</span> <span class="token5">null</span>也會輸出字符串
<span class="token">!</span><span class="token">!</span><span class="token4">"3.5"</span> <span class="token3">true</span>
typeof <span class="token5">null</span><span class="token2">;</span> object
```
```
- 字符串
```
<pre class="calibre14">```
<span class="token4">"123我愛你"</span><span class="token2">.</span><span class="token1">charAt</span><span class="token2">(</span><span class="token3">3</span><span class="token2">)</span> 返回我<span class="token2">,</span><span class="token3">3</span>是位置
<span class="token4">"123我愛你"</span><span class="token2">.</span><span class="token1">indexOf</span><span class="token2">(</span><span class="token4">"我"</span><span class="token2">)</span> 返回<span class="token3">3</span> 找不到<span class="token">-</span><span class="token3">1</span>
<span class="token4">"123我愛你"</span><span class="token2">.</span><span class="token1">match</span><span class="token2">(</span><span class="token">/</span>愛<span class="token2">(</span><span class="token2">.</span><span class="token">*</span><span class="token2">)</span><span class="token">/</span><span class="token2">)</span> 返回數組 <span class="token2">[</span><span class="token4">"愛你"</span><span class="token2">,</span> <span class="token4">"你"</span><span class="token2">]</span> 沒有找到返回 <span class="token5">null</span>
<span class="token4">"我愛你中國美國英國"</span><span class="token2">.</span><span class="token1">substring</span><span class="token2">(</span><span class="token3">1</span><span class="token2">,</span><span class="token3">4</span><span class="token2">)</span><span class="token2">;</span> 返回愛你中<span class="token2">,</span>從第<span class="token3">1</span>到<span class="token3">4</span>不包括<span class="token3">4</span>
<span class="token4">"我愛你中國美國英國"</span><span class="token2">.</span><span class="token1">substr</span><span class="token2">(</span><span class="token3">3</span><span class="token2">,</span><span class="token3">5</span><span class="token2">)</span> 第三個開始截取<span class="token3">5</span>個字符
<span class="token4">"我愛你中國人"</span><span class="token2">.</span><span class="token1">replace</span><span class="token2">(</span><span class="token">/</span>中國<span class="token">/</span><span class="token2">,</span><span class="token4">"美國"</span><span class="token2">)</span><span class="token2">;</span>
<span class="token4">"我愛你中國人"</span><span class="token2">.</span><span class="token1">search</span><span class="token2">(</span><span class="token">/</span>中國<span class="token">/</span><span class="token2">)</span><span class="token2">;</span> 找到返回下標 沒找到返回<span class="token">-</span><span class="token3">1</span>
<span class="token4">"123我愛你"</span><span class="token2">.</span><span class="token1">split</span><span class="token2">(</span><span class="token4">""</span><span class="token2">)</span><span class="token2">;</span> 返回數組 支持正則
<span class="token4">"aA"</span><span class="token2">.</span><span class="token1">toLowerCase</span><span class="token2">(</span><span class="token2">)</span><span class="token2">;</span>轉小寫 toUpperCase大寫
var string <span class="token">=</span> <span class="token2">(</span><span class="token3">2</span><span class="token2">)</span><span class="token2">.</span><span class="token1">toString</span><span class="token2">(</span><span class="token2">)</span><span class="token2">;</span>
var string <span class="token">=</span> <span class="token3">2</span><span class="token">+</span><span class="token4">''</span><span class="token2">;</span>
```
```
- 數組
```
<pre class="calibre14">```
var arr <span class="token">=</span><span class="token1">Array</span><span class="token2">(</span><span class="token3">1</span><span class="token2">,</span><span class="token3">2</span><span class="token2">,</span><span class="token3">3</span><span class="token2">)</span><span class="token2">;</span>
var arr <span class="token">=</span><span class="token2">[</span><span class="token3">1</span><span class="token2">,</span><span class="token3">2</span><span class="token2">,</span><span class="token3">3</span><span class="token2">]</span><span class="token2">;</span>
var arr <span class="token">=</span><span class="token2">{</span><span class="token4">"31536000"</span><span class="token2">:</span><span class="token4">"年"</span><span class="token2">,</span><span class="token4">"2592000"</span><span class="token2">:</span><span class="token4">"個月"</span><span class="token2">,</span><span class="token4">"604800"</span><span class="token2">:</span><span class="token4">"星期"</span><span class="token2">,</span><span class="token4">"86400"</span><span class="token2">:</span><span class="token4">"天"</span><span class="token2">,</span><span class="token4">"3600"</span><span class="token2">:</span><span class="token4">"小時"</span><span class="token2">,</span><span class="token4">"60"</span><span class="token2">:</span><span class="token4">"分鐘"</span><span class="token2">,</span><span class="token4">"1"</span><span class="token2">:</span><span class="token4">"秒"</span><span class="token2">}</span><span class="token2">;</span>
<span class="token2">[</span><span class="token3">1</span><span class="token2">,</span><span class="token3">2</span><span class="token2">,</span><span class="token3">3</span><span class="token2">]</span><span class="token2">.</span><span class="token1">join</span><span class="token2">(</span><span class="token4">','</span><span class="token2">)</span><span class="token6">//數組轉換字符串</span>
<span class="token4">'1,2,3'</span><span class="token2">.</span><span class="token1">split</span><span class="token2">(</span><span class="token4">','</span><span class="token2">)</span><span class="token6">//字符串轉換數組</span>
$<span class="token2">.</span><span class="token1">isArray</span><span class="token2">(</span><span class="token2">[</span><span class="token2">]</span><span class="token2">)</span><span class="token2">;</span><span class="token6">// 是否數組 返回true</span>
arr<span class="token2">.</span><span class="token1">push</span><span class="token2">(</span><span class="token4">"white"</span><span class="token2">,</span><span class="token4">"test"</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//尾部插入數組值 返回長度</span>
arr<span class="token2">.</span><span class="token1">unshift</span><span class="token2">(</span><span class="token4">"first"</span><span class="token2">)</span><span class="token2">;</span> <span class="token6">//頭部插入</span>
arr<span class="token2">.</span><span class="token1">pop</span><span class="token2">(</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//尾部刪除 返回被刪除元素</span>
arr<span class="token2">.</span><span class="token1">shift</span><span class="token2">(</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//頭部刪除</span>
arr<span class="token2">.</span><span class="token1">reverse</span><span class="token2">(</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//顛倒數組</span>
arr<span class="token2">.</span><span class="token1">sort</span><span class="token2">(</span><span class="token5">function</span><span class="token2">(</span>num1<span class="token2">,</span> num2<span class="token2">)</span> <span class="token2">{</span> <span class="token5">return</span> num1 <span class="token">></span> num2<span class="token2">;</span><span class="token2">}</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//排序 返回排序后</span>
arr<span class="token2">.</span><span class="token1">concat</span><span class="token2">(</span><span class="token2">[</span><span class="token4">"ccc"</span><span class="token2">,</span><span class="token4">"bbbb"</span><span class="token2">]</span><span class="token2">,</span><span class="token4">'3333'</span><span class="token2">,</span><span class="token2">[</span><span class="token4">'vvccxx'</span><span class="token2">,</span><span class="token2">[</span><span class="token4">'oolll'</span><span class="token2">,</span><span class="token4">'lll'</span><span class="token2">]</span><span class="token2">]</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//合并數組 返回新數據</span>
arr<span class="token2">.</span><span class="token1">slice</span><span class="token2">(</span><span class="token3">1</span><span class="token2">,</span><span class="token3">3</span><span class="token2">)</span><span class="token2">;</span> <span class="token6">//復制數組 從第一個開始第三個結束 返回新數組</span>
arr<span class="token2">.</span><span class="token1">splice</span><span class="token2">(</span><span class="token3">0</span><span class="token2">,</span><span class="token3">2</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//刪除前兩個</span>
arr<span class="token2">.</span><span class="token1">splice</span><span class="token2">(</span><span class="token3">1</span><span class="token2">,</span><span class="token3">1</span><span class="token2">,</span><span class="token3">100</span><span class="token2">,</span><span class="token3">200</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//從第二個刪除1個 并添加2個新元素</span>
var max <span class="token">=</span> Math<span class="token2">.</span>max<span class="token2">.</span><span class="token1">apply</span><span class="token2">(</span>Math<span class="token2">,</span> arr<span class="token2">)</span> <span class="token6">//3</span>
var min <span class="token">=</span> Math<span class="token2">.</span>min<span class="token2">.</span><span class="token1">apply</span><span class="token2">(</span>Math<span class="token2">,</span>arr<span class="token2">)</span> <span class="token6">//1</span>
arr<span class="token2">.</span><span class="token1">indexOf</span><span class="token2">(</span>str<span class="token2">)</span><span class="token2">;</span><span class="token6">//查找元素位置 字符操作</span>
var arr<span class="token">=</span><span class="token2">[</span><span class="token4">"中國"</span><span class="token2">,</span><span class="token4">"美國"</span><span class="token2">,</span><span class="token4">"日本"</span><span class="token2">,</span><span class="token4">"韓國"</span><span class="token2">]</span><span class="token2">;</span>
arr<span class="token2">.</span><span class="token1">forEach</span><span class="token2">(</span><span class="token5">function</span><span class="token2">(</span>v<span class="token2">,</span>k<span class="token2">)</span><span class="token2">{</span>
<span class="token1">log</span><span class="token2">(</span>k<span class="token2">)</span>無返回值
<span class="token2">}</span><span class="token2">)</span>
arr<span class="token2">.</span><span class="token1">map</span><span class="token2">(</span><span class="token5">function</span><span class="token2">(</span>value<span class="token2">,</span>index<span class="token2">,</span>array<span class="token2">)</span><span class="token2">{</span>
<span class="token5">return</span> XXX
<span class="token2">}</span><span class="token2">)</span>
```
```
- json與對象
```
<pre class="calibre14">```
var str <span class="token">=</span> <span class="token4">'{"a":"2a","b":true,"c":34,"d":[1,2,"a"]}'</span><span class="token2">;</span><span class="token6">//json操作</span>
JSON<span class="token2">.</span><span class="token1">parse</span><span class="token2">(</span>str<span class="token2">)</span><span class="token2">;</span><span class="token6">//json字符串轉換成對象</span>
var obj <span class="token">=</span> <span class="token1">eval</span><span class="token2">(</span><span class="token4">'('</span> <span class="token">+</span> str <span class="token">+</span> <span class="token4">')'</span><span class="token2">)</span><span class="token2">;</span><span class="token6">//3種方法</span>
var k1 <span class="token">=</span> <span class="token2">{</span>a<span class="token2">:</span><span class="token3">1</span><span class="token2">,</span>b<span class="token2">:</span><span class="token2">[</span><span class="token3">1</span><span class="token2">,</span><span class="token3">2</span><span class="token2">]</span><span class="token2">}</span><span class="token2">;</span><span class="token6">//對象</span>
var k2 <span class="token">=</span> <span class="token2">{</span><span class="token4">"k1"</span><span class="token2">:</span><span class="token3">1</span><span class="token2">,</span><span class="token4">"k2"</span><span class="token2">:</span><span class="token4">"中國"</span><span class="token2">}</span><span class="token2">;</span><span class="token6">//json標準格式 或者是關聯數組</span>
JSON<span class="token2">.</span><span class="token1">stringify</span><span class="token2">(</span>k1<span class="token2">)</span> <span class="token6">//json對象轉換成字符串</span>
```
```
- 時間戳13位長
```
<pre class="calibre16">```
<span class="token">+</span><span class="token5">new</span> <span class="token1">Date</span><span class="token2">(</span><span class="token2">)</span> 當前時間戳
<span class="token">+</span><span class="token5">new</span> <span class="token1">Date</span><span class="token2">(</span><span class="token4">'2014/12/24 02:08:01'</span><span class="token2">)</span><span class="token2">;</span> 轉換時間戳
Date<span class="token2">.</span><span class="token1">now</span><span class="token2">(</span><span class="token2">)</span> 當前時間戳
<span class="token5">new</span> <span class="token1">Date</span><span class="token2">(</span>Date<span class="token2">.</span><span class="token1">parse</span><span class="token2">(</span><span class="token4">"2012-12-15 09:41:30"</span><span class="token2">.</span><span class="token1">replace</span><span class="token2">(</span><span class="token">/</span><span class="token">-</span><span class="token">/</span>g<span class="token2">,</span><span class="token4">"/"</span><span class="token2">)</span><span class="token2">)</span><span class="token2">)</span><span class="token2">;</span> Date對象
<span class="token5">new</span> <span class="token1">Date</span><span class="token2">(</span><span class="token3">1419184274000</span><span class="token2">)</span> Date對象
```
```
- 簡介
- 第一章 數據庫
- Mysql/mariadb
- 函數
- 基礎
- 增刪改索引
- 標準查詢
- 高級查詢
- TIDB集群mysql解決方案
- Redis
- 語言基礎
- 5種數據類型
- 其他類型
- Sqlite
- 語言基礎
- 常用查詢
- 第二章 PHP
- 語言基礎
- 第一課 流程控制和運算
- 第二課 數組
- 第三課 日期時間
- 第四課 常用函數
- 第五課 字符串
- 第六課 文件操作
- 第七課 面向對象
- 第八課 正則表達式
- 第九課 圖片處理生成
- 第十課 curl/memche
- 第十一課 mysql和pdo
- 第十三課 cookie和session
- 第十四課 xml操作
- 第十五課 php5.3+新特性
- 第十六課 php7+
- 第十七課 密碼安全
- 廢棄函數
- php命令行
- redis應用
- 算法
- 排序算法
- 基礎算法
- 無限級分類
- 自定義函數Fn
- 查找算法
- 自定義函數數據函數fn
- laravel
- 路由
- 常用語句
- 數據庫
- dingo/api
- Yii2
- 控制器
- 常用類
- 數據庫
- redis
- thinkphp6
- TP6文檔
- TP6插件
- dedecms
- 織夢標簽大全
- 數據庫操作
- 內置函數和定義函數
- 織夢核心改動
- 織夢插件/底層標簽開發
- PHP相關工具
- composer
- php開發環境phpenv
- Phpstorm使用
- windows編譯php擴展
- PHP開源庫
- 開源項目管理禪道
- sns_auth
- php-casbin權限控制
- php-jwt
- 微信SDKeasywechat
- querylist采集庫
- workerman
- Box/Spout處理excel和csv
- dll擴展
- redis/memche/xdebug
- redis
- Lua
- php_xlswriter
- event
- swoole
- 常用代碼庫
- 微擎框架
- 第一課全局變量
- 第二課常用函數
- 第三課自定義微擎獨有函數
- 第四課數據庫操作
- 第五課微信端回復
- 第六課微擎高級操作
- 第八課global函數列表
- mainfest.xml詳解
- js方法
- 人人商城
- 第一課model解讀
- 第二課常用語句解讀
- 第三課常用js解讀
- 第四課附錄常見問題
- 第五課附錄處理報表|支付
- 常用JSON狀態碼
- 第三章 JavaScript
- js基礎
- 瀏覽器對象
- 語言基礎
- html5接口
- ES6新語法
- vue
- 基礎語法
- 京東vueUI組件
- uniapp
- 組件開發規范
- nodejs
- 基礎知識
- 安裝node
- nvm不同版本node切換
- js常用標準庫
- zepto/jquery
- weui
- js圖標庫
- elementUI
- validator表單驗證
- layer彈出層
- requirejs
- wow動畫
- 動畫animate
- swiper4
- 百度編輯器
- flyio/axios/qs
- jquery.form
- bootstrap3
- clipboard復制
- slideout側滑
- imagehover.css圖片懸停動畫
- webpack打包
- Bulma UI框架
- store 客戶端存儲
- lottie動畫創建庫
- sweetalert
- js自定義函數
- 常見JSSDK
- 微信公眾號JSSDK
- 騰訊地圖jssdk
- 微信小程序
- 第四章 編程語言
- markdown語言
- Dart語言
- Dart語言基礎
- Flutter框架
- Lua語言
- 字符串,數組,表
- 自定義方法
- go語言
- 第1.1語言基本語法
- 第1.2流程控制
- 第1.3函數
- 第1.4結構體
- 第1.5接口
- 第1.6包
- go語言框架Gin
- CSS3語言
- CSS與CSS3
- 選擇符
- 屬性
- css3
- loading動畫
- HTML5語言
- less
- sass
- C#
- 基礎知識
- 函數
- 第五章 開發工具
- git
- nginx/apache服務器
- Linux常用操作
- crontab定時任務
- 注冊表與cmd
- 阿里云ECS
- frp穿透和ssl續期
- 寶塔安裝
- 樹莓派
- 瀏覽器模擬
- 火狐/chrome常用插件
- WSL安裝使用
- mac brew和終端命令
- win10相關