javascript练习

2022/3/19 17:57:37

本文主要是介绍javascript练习,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
<!--   <script type="text/javascript">
       alert("hello javaScript");
    </script>

    <script type="text/javascript" src="1.js"></script>-->
 <!--     <script type="text/javascript">
            var i;
            alert(i);//undefined
            i=12;
            alert(typeof(i));//number;

            i="abc";
            alert(typeof(i));//string

            var a=12;
            var b="abc";
            alert(a*b);//Nan

            var a="12";
            var b=12;
            alert(a==b);
            alert(a===b);
        </script>-->
   <!-- <script type="text/javascript">
        var a=0;
        if(a){
            alert("0为真");
        }else{
            alert("0为假");
        }
        var b=null;
        if(b){
            alert("null为真");
        }else{
            alert("null为假");
        }
        var c=undefined;
        if(c){
            alert("undefined为真");
        }else{
            alert("undefined为假");
        }
        var d="";
        if(d){
            alert("空串为真");
        }else{
            alert("空串为假");
        }
    </script>-->
   <!-- <script type="text/javascript">
        var a="abc";
        var b=true;
        var c=false;
        var d=null;
        alert(a&&b);//true
        alert(a&&c);//false
        alert(c&&a);//false
        alert(a&&d);//null

        alert(a||d);//abc
        alert(d||a);//abc
        alert(d||c);//false
        alert(c||d);//null
    </script>-->
   <!-- <script type="text/javascript">
        var arr=[true,1];
        for(var i=0;i<arr.length;i++){//true ,1
            alert(arr[i]);//12 1 abc
        }
        alert(arr.length);//2
        arr[0]=12;
        alert(arr[0]);//12
        alert((arr.length));//2
        arr[2]="abc";
        alert(arr.length);//3
        alert(arr[1]);//1
        for(var i=0;i<arr.length;i++){
            alert(arr[i]);//12 1 abc
        }
    </script>-->
  <!--  <script type="text/javascript">
        function fun() {
            alert("无参函数fun()被调用了");

        }
        fun();
        function fun2(a,b) {
            alert("有参函数fun2()被调用了 a=>"+a+",b=>"+b);

        }
        fun2(12,"abc");
        function sum(num1,num2) {
            var result=num1+num2;
            return result;

        }
        alert(sum(100,50));
    </script>-->
  <!--  <script type="text/javascript">
       function fun(a) {
           alert(arguments.length);
           alert(arguments[0]);
           alert(arguments[1]);
           alert(arguments[2]);
           alert("a="+a);
           for (var i=0;i<arguments.length;i++){
               alert(arguments[i]);
           }

       }
       function sum(num1,num2) {
           var result=0;
           for (var i=0;i<arguments.length;i++){
               if(typeof(arguments[i])=="number"){
                   result+=arguments[i];
               }
           }
           return result;

       }
       alert(sum(1,2,3,4,"abc",5,6,7,8,9));
    </script>-->
    <!--<script type="text/javascript">
        var obj=new Object();
        obj.name="华仔";
        obj.age=18;
        obj.fun=function(){
            alert("姓名:"+this.name+" ,年龄:"+this.age);
        }
        obj.fun();
    </script>-->
    <script type="text/javascript">
        var obj={
            name:"国哥",
            age:18,
            fun:function () {
                alert("姓名:"+this.name+",年龄:"+this.age);

            }
        };
        alert(obj.name);
        obj.fun();
    </script>
    </head>
    <body>

    </body>
    </html>


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