console 命令行工具 X clear

console

//单向选择
var x=3;
if(x>1){
    document.write(x+"<br/>");

}

document.write('<br/>-----------------<br/>');

//双向选择
var x=3;
if(x>1){
    x--;
    document.write(x+"<br/>");
}    

else{
    x;
}
document.write('<br/>-----------------<br/>');

//多向选择
var y=1;
if(y>1){
     y--;
    document.write(y+"<br/>");
}    

else if(y==1){
    document.write(y+"<br/>");
}

else{
    0;
}

document.write('<br/>-----------------<br/>');

//if的嵌套
var b = 5;
var c = 3;
if(b>=5){
    if(c>2){
       document.write(b+"<br/>");
    }

    else{
          
        document.write(c+"<br/>");
    }
}

else{

       if(c>4){
       document.write(b+"<br/>");
    }

    else{
          
        document.write(c+"<br/>");
    }
}

document.write('<br/>-----------------<br/>');

//判断一个数是整数，还是小数？
function isInterger(num){
    var result = false; 
    if (parseInt(num) == parseFloat(num))
	{
		result=true;		
    }
    //return result;
    else{
         result = false;
    }

}

   var num =  3.14;
if(isInterger(3.14)){

    document.write("15 is an integer."+"<br/>");
}

else
{
    document.write(num + "是小数"+"<br/>");
}

document.write('<br/>-----------------<br/>');

//找出“水仙花数”
function findDaffodilNum(){
    document.write("水仙花数有: "+"<br/>");

        for (var num = 100; num < 1000; num++)
        {    
            //提取个位数
            var a = num % 10;    

            //提取十位数
            var b = (num / 10) % 10     
            b = parseInt(b);            //舍弃小数部分

            //提取百位数
            var c = num / 100;            
            c = parseInt(c);            //舍弃小数部分  

            if (num == (a * a * a + b * b * b + c * c * c)) 
            {
               document.write(num +"<br/>");
            }
        }

}
findDaffodilNum();
document.write('<br/>-----------------<br/>');

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
        var a= 3;
        document.write(a+"<br/>");
    </script>
</head>
<body>
</body>
</html>