console 命令行工具 X clear

console

//document.write("Welcome")

var A=10;
        var b=3.14;
        var string="hello";
        var notDefined;
        var noSpace=null;
        document.write(A+"<br/>");
        document.write(b+"<br/>");
        document.write(string+"<br/>");
        document.write(notDefined+"<br/>");
        document.write(noSpace+"<br/>");
document.write("............................<br/>")
        var number1=12;
        var number2=16;
        var string1="hi";
        var string2="hier";
        var sum1=number1+number2;
        var sum2=string1+string2;
        var sum3=number1+string1;
        var sum4=number1+"";
        document.write(sum1+"<br/>");
        document.write(sum2+"<br/>");
        document.write(sum3+"<br/>");
        document.write(sum4+number2+"<br/>");

        document.write("............................<br/>")



        //赋值运算符
        var a=1;
        var b=2;

        document.write(a+"<br/>")
        document.write(b+"<br/>")

        a+=b;
        document.write(a+"<br/>");
        a-=b;
        document.write(a+"<br/>");
        a*=b;
        document.write(a+"<br/>");
        a/=b;
        document.write(a+"<br/>");
   document.write("............................<br/>");
   //比较运算
   var large =(1+2) >(2+3);
   document.write("(1+2) >(2+3):"+large+"</br>");

    var smaller =(1+2) <(2+3);
   document.write("(1+2) <(2+3):"+smaller+"</br>");

   var largeequal =(1+2) >=(2+3);
   document.write("(1+2) >(2+3):"+largeequal+"</br>");

      var smallerequal =(1+2) <=(2+3);
   document.write("(1+2) >(2+3):"+smallerequal+"</br>");

   var equal =((2+2)==4)
   document.write("(2+2)==4:"+equal+"</br>");

     var notequal =((2+2)!=4)
   document.write("(2+2)!=4:"+notequal+"</br>");

   document.write("............................<br/>");
   //逻辑运算
   var intersection=true && (1>2); 
   document.write("true && (1>2):"+intersection+"</br>");

   var union=true || (1>2); 
   document.write("true || (1>2):"+union+"</br>");

   var not=!(1>2); 
   document.write("! (1>2):"+not+"</br>");

    document.write("............................<br/>");
   //条件运算
   var condition=(3>5)?"你":"我";
   document.write('(3>5)? "你" : "我": '+condition+"</br>");

    document.write("............................<br/>");
    //字符串转数字
    var a = Number("2018") + 1000;
     document.write(a+"</br>");

     document.write("Number('123')：" + Number("123") + "<br/>");
    document.write("Number('3.1415')：" + Number("3.1415") + "<br/>");
    document.write("Number('hao123')：" + Number("hao123") + "<br/>");
    document.write("Number('100px')：" + Number("100px"));

    document.write("parseInt('123')：" + parseInt("123") + "<br/>");
    document.write("parseInt('3.1415')：" + parseInt("3.1415") + "<br/>");
    document.write("parseInt('hao123')：" + parseInt("hao123") + "<br/>");
    document.write("parseInt('100px')：" + parseInt("100px"));

    document.write("............................<br/>");
    //数字转字符串
    var a = 2018 + "";
    var b = a + 1000;
    document.write(b+"</br>");

    var a = 2018;
    var b = a.toString() + 1000;
    document.write(b+"</br>");

    document.write("............................<br/>");
    //转义字符
    document.write("绿叶，给你\"初恋\"般的感觉~");

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <script>
        //变量
        var a=23;
        document.write(a+"<br/>"); 
        var b=34;


        var A=10;//常量
        var b=3.14;//变量
        var string="hello";//字符串
        var notDefined;//未定义的值
        var noSpace=null;//空值
        document.write(A+"<br/>");
        document.write(b+"<br/>");
        document.write(string+"<br/>");
        document.write(notDefined+"<br/>");
        document.write(noSpace+"<br/>");

        //加法运算的特别
        var number1=12;
        var number2=16;
        var string1="hi";
        var string2="hier";
        var sum1=number1+number2;//数字和数字
        var sum2=string1+string2;//字符串与字符串
        var sum3=number1+string1;//数字与字符串
        var sum4=number1+"";
        document.write(sum1+"<br/>");
        document.write(sum2+"<br/>");
        document.write(sum3+"<br/>");
        document.write(sum4+number2+"<br/>");




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