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

var smaller=(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":'+"我"+"<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('3.1415')：" + 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”转换为“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~"+ "<br/>");

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

document.write("绿叶，<br/>初恋般的感觉~"+ "<br/>");

<!DOCTYPE html>
<html>
<head>  
    <mata charset="utf=8"/>
</head>
<body>
    <script>


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