常用字符串与数组方法学习 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // let name ="a"
        // let email = name;
        // console.log(email);

        console.log(String.prototype);

        // 1.concat():字符串拼装学习
        // 方法一：加号拼接字符串
        let str = "html" + ", css" + ", js";
        console.log(str);
        // 方法二：函数拼接字符串：便于集合化处理
        str = "html".concat(", css", ", js");
        console.log(str);

        // 2.slice(start开始 , end结束):从子串
        str = "hello php.cn";
        // h-0
        // e-1
        // l-2
        // l-3
        // 0-4
        // 空格-5 结果中不包括结束索引的字符
        let res = str.slice(0,5);
        console.log(res);

        res = str.slice(0);
        console.log(res);

        res = str.slice(5);
        console.log(res);

        res = str.slice(-1);
        console.log(res);

        res = str.slice(-2);
        console.log(res);

        res = str.slice(-3);
        console.log(res);

        // 2.1取子串
        res = str.substr (0,5);
        console.log(res);

        res = str.substr(-6,3);
        console.log(res);

        res = str.substr(-10,2);
        console.log(res);

        // 3.trim();删除两边的二空白字符
        let psw1 = "admin123";
        let input = "admin123";
        console.log(psw1 === input);

         psw1 = "admin123";
         input = "  admin123  ";
         console.log(psw1 === input);

         psw1 = "admin123";
         input = "  admin123  ";
         console.log(input.length);
         input = input.trim();
         console.log(input);
         console.log(psw1 === input);

        //  字符转数组
        res = str.split("");
        console.log(res);

        res = str.split(" ");
        console.log(res);

        console.log("" === " ");

        console.log("html-css-js".split("-"));

        let email = "498668472@qq.con";
        res = email.split("@");
        console.log(res);
        console.log("账号:%s",res[0]);
    </script>
</body>
</html>

　　

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>

        // 1.push尾部添加
         let arr = [];
         arr.push(4);
         console.log(arr);
         console.log(arr.push("a"));
         console.log(arr);
         console.log(arr.push("b","c","d"));
         console.log(arr);

        //  2.pop尾部删除
        console.log(arr.pop());
        console.log(arr);
        console.log(arr.pop());
        console.log(arr);
        

        // 3.unshift();头部添加
        console.log(arr.unshift(1,2,3));
        console.log(arr);

        // 4.shift()头部删除
        console.log(arr.shift());
        console.log(arr.shift());
        console.log(arr.shift());
        console.log(arr);

        



    </script>
</body>
</html>

　　

posted @ 2024-06-08 17:06  豹纹守宫  阅读(22)  评论(0)    收藏  举报