console 命令行工具 X clear

console

var $a = 10;
var a = 3.14;
var string = "I am a string";
var notDefined;
var noSpace = null;
document.write($a+"<br/>");
document.write(a+"<br/>");
document.write(string+"<br/>");
document.write(notDefined+"<br/>");
document.write(noSpace+"<br/>");
document.write("----------------------------------<br/>")

var number1 = 10;
var number2 = 20;
var sum=number1+number2;
var string1 = "Hi";
var string2 = "Heather";
var string1Number1 =  string1 +number1;
var number2String2 = number2+string2;
var stringNumber1 = number1 + "";
var stringNumber1Number2 = stringNumber1 + number2;
        
document.write(sum+"<br/>");
document.write(string1Number1+"<br/>");
document.write(number2String2+"<br/>");
document.write(stringNumber1Number2+"<br/>");
document.write(string1 + string2 +"<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/>");
//比较运算符
var larger = (1+2)>(2+3);
document.write("(1+2)>(2+3):" + larger + "</br>");
var smaller = (1+2)<(2+3);
document.write("(1+2)<(2+3):" + larger + "</br>");
var largeEqual = (1+2)>=(2+1);
document.write("(1+2)>=(2+3):" +largeEqual + "</br>");
var smallerEqual = (1+2)<=(2+3);
document.write("(1+2)<=(2+3):" + larger + "</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/>");
//逻辑运算符
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/>");
//条件运算符
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")+"</br>");

document.write("parseInt('123'):"+parseInt('123')+"</br>");
document.write("parseInt('3.14'):"+parseInt('3.1415')+"</br>");
document.write("parseInt('hao123'):"+parseInt('hao123')+"</br>");
document.write("parseInt('100px'):"+parseInt('100px')+"</br>");
document.write("parseInt('+123'):"+parseInt('+123')+"</br>");
document.write("parseInt('-123'):"+parseInt('-123')+"</br>");

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

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>
    <mata charset="utf-8"/>
</head>
<body>
    <script>


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