console 命令行工具 X clear
console
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
</head>

<body>
	
	
	<script>
      
		
		
		
		function test1(){
			var a=1,b=2;
			return a+b;
			
		}
		
		function test2(){
			alert("测试成功");
		}
		
		var cs=test1()+3;
		document.write(cs+"<br/>");

        function run(x){
			if(x%4==0&&x%100!=0){
				document.write(x+"是闰年<br/>");
			}
			else if(x%400==0){
				document.write(x+"是闰年<br/>");
			}
			else{
				document.write(x+"不是闰年<br/>");
			}
		}
		run(2020);
		run(2000);
		run(2001);

        function tx(a,b,c,d){
                var max=0;
                max=a>b?a:b;
                max=c>max?c:max;
                max=d>max?c:max;
                document.write("最大值为"+max+"<br/>")
        }
        var a=23,b=34,c=2,d=6;
        tx(a,b,c,d);

        document.write("---------------------------------"+"<br/>");

        var s3="sadDHKJFHKJ";
        document.write(s3.toLowerCase()+"<br/>");
        document.write(s3.toUpperCase()+"<br/>");
       
		
		document.write(s3.charAt(2)+"<br/>");
		document.write(s3.charAt(5)+"<br/>");
		
		
		document.write(s3.substring(1,6)+"<br/>");
		document.write(s3.replace("sad","abc")+"<br/>");
		
		document.write(s3.split("")+"<br/>");

        var str1 = "今天天气真好";
        var str2 = str1.substring(1,3);
        document.write(str2+"<br/>");

        var str = "I am low, you are low, all are low.";
        var str_new = str.replace(/low/g, "hh");
        document.write(str_new);

var ss="go class go class";
		document.write(ss.indexOf("class")+"<br/>");//第一个的位置
		document.write(ss.lastIndexOf("class")+"<br/>");//最后一个的位置
		document.write(ss.match("class")+"<br/>");//有则返回第一个，否则返回null
		document.write(ss.match(/class/g)+"<br/>");//有则返回所有,否则返回null
		document.write(ss.search(/class/g)+"<br/>");//返回第一个的位置,否则返回-1

        var s1="Can you can a can as a Canner can can a can";
		var n1=0;
	function tj(){
		for(var i=0;i<s1.length;i++){
			var s2=s1[i].toLowerCase();
			if(s2=="c"){
				n1++;
			}
			
		}
		return n1;
	}
        document.write("共有"+tj()+"个c"+"<br/>");

    var arr=["HTML","CSS","JavaScript","jQuery","Vue.js" ];
    for(var i=0;i<arr.length;i++){
        document.write(arr[i]+"<br/>");

    }

    arr [5]="aaa";
    arr [7]="bbb";
    arr[10]="ccc";
    document.write(arr);

    var s4="5fgfd432432d";
    function tjx(){
		var x=0;
        for(var i=0;i<s4.length;i++){
				if(s4[i]!=" " && !isNaN(s4[i])){
					x++;
				}
		}
		document.write("该字符串共有"+x+"个数字");
    }
    tjx();

    </script>
	<br/>
	<a href="javascript:test2()">函数超链接调用</a>

    

    
</body>
</html>