4 JS - 基础 

<!DOCTYPE html>
<html>
<head> 
    <meta charset="utf-8"> 
    <title>lizi_test</title> 
</head>
<body>
    <div>
        <button type="button" onclick="test()">点我体验JS学习</button>
        <button type="button" onclick="testIf(15)">点我体验JS if学习</button>

        <p>JS学习</p>
        <ul>
            <li>var 定义变量</li>
            <li>分号用于分隔JS语句</li>
            <li>function myFunction(){}定义方法</li>
            <li>//注释单行内容</li>
            <li>/**/注释多行内容</li>
            
            <p>JS数据类型</p>
            <ul>
                <p>值类型(基本类型)</p>
                <li>字符串（String）</li>
                <li>数字(Number)</li>
                <li>布尔(Boolean)</li>
                <li>对空（Null）</li>
                <li>未定义（Undefined）</li>
                <li>独一无二（Symbol）</li>
                
                <p>引用数据类型</p>
                <li>对象(Object)</li>
                <li>数组(Array)</li>
                <li>函数(Function)</li>
            </ul>
        </ul>
    <p> 
        concat()      连接两个或多个字符串<br>
        match()       找到一个或多个正则表达式的匹配<br>
        replace()     替换与正则表达式匹配的子串<br>
        split()       分割字符串为数组<br>
        toLowerCase() 字符串转小写<br>
        toUpperCase() 字符串转大写<br>
        trim()        移除字符串首尾空格<br>                 
    </p>
        
    </div>
    
    <script type="text/javascript">
        var t;
        var t1=null
        var length = 6;                                  // Number 通过数字赋值
        var points = length * 6;                         // Number 通过表达式赋值
        var name = "lizi";                               // String 通过字符串赋值
        var fruits = ["apple", "orange", "banana"];      // Array  通过数组赋值
        var person = {
            firstName:"li", 
            lastName:"zi",
            fullName : function() 
            {
               return this.firstName + " " + this.lastName;
            }
        };                // Object 通过对象赋值
        function test(){  // 函数
            console.log(t);
            console.log(t1);
            console.log(length);
            console.log(points);
            console.log(name);
            console.log(fruits);
            console.log(person);
            console.log(person.firstName);
            console.log(person["lastName"]);
            console.log(person.fullName());
        }
        function testIf(x){
            if (x<10)
            {
                console.log("(x<10");
            }
            else if (x>=10 && x<20)
            {
                console.log("x>=10 && x<20");
            }
            else
            {
                console.log("hahaha");
            }
        }
        for (var i=0; i<5; i++)
        {
              console.log("x = " + i);
        }
        var cars=["BMW","Volvo","Saab","Ford"];
        for (var i=0,l=cars.length; i<l; i++){
            console.log("第" + i + "个汽车是：" + cars[i]);
        }
            var person2={fname:"Bill",lname:"Gates",age:56}; 
        for (x in person2){
            var txt="";
            txt=txt + ;
            console.log(person2[x]);} 

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

 

posted @ 2021-03-27 23:58  栗子测试开发  阅读(128)  评论(0)    收藏  举报