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JavaScript statement structure

PHP中文网Original: 2017-06-22 13:44:241411browse

1. Experience

Put the constants on the left side when judging
switch in java only supports four types, and javaScript is a weak type, all of which are supported.

Display method:

               alert("x="+x);
             //将数据直接写到当前页面当中。
              document.write("x="+x+"<br/>");

2. Code

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=GBK">
        <title>Untitled Document</title>
    </head>
    <body>
        <script type="text/javascript">
            /*
             * 语句：
             * 1，顺序结构。
             *     
             * 2，判断结构。
             *         代表语句： if.
             * 3，选择结构。
             *         switch
             * 4，循环结构。
             *         while  do while  for
             * 5，其他语句。
             *         break：跳出选择，跳出循环。
             *         continue:用于循环语句，结束本次循环继续下次循环。 
             */
            
//            alert("abc1");
//            alert("abc2");
        
        
//            ------------------------------------------------
            /*
            var x = 3;
//            if(x=4){//注意。
            if(4==x){//建议将常量放左边。以报错来修正代码。
                alert("yes");
            }else{
                alert("no");
            }
            
            
            
            if(x>1)
                alert("a");
            else if(x>2)
                alert("b");
            else if(x>3)
                alert("c");
            else
                alert("d");
                
            */    
        
//            ------------------------------------------------
            /*
            //选择结构。
            var x = "abc";
            switch(x){
                
                case "kk":
                    alert("a");
                    break;
                case "abc":
                    alert("b");
                    break;
                default:
                    alert("c");
                    break;//省略。因为是最后一个语句，后面就是大括号了    
            }
            */
            
            
            
            //循环结构。
            /*
            var x = 1;
            document.write("<font color=&#39;blue&#39; >");//颜色控制，html内容
            while(x<10)
            {
//                alert("x="+x);
                //将数据直接写到当前页面当中。
                document.write("x="+x+"<br/>");
                x++;
            }
            document.write("</font>");
            
            
            for(var x=0; x<3; x++){
                document.write("x="+x);
            }
            */
            
            
            /*
            w:for(var x=0; x<3; x++){//标号
                for(var y=0; y<4; y++){
                    document.write("x==="+x);
                    continue w;//跳出当前循环。
                }
            }
            */
            
            
        </script>
        
        
        
        
    </body>
</html>

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JavaScript statement structure

1. Experience

2. Code

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