console
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
</script>
</head>
<body>
<script>
var $a=10;
var a=3.14;
var string = "hello world";
var notDefined;
var noSpace = null;
document.write($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 = "hello";
var string2 = " world";
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/>");
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/>");
var larger=(1+2)>(2+3);
document.write("(1+2)>(2+3):"+larger+"<br/>");
var larger=(1+2)<(2+3);
document.write("(1+2)<(2+3):"+larger+"<br/>");
var larger=(1+2)>=(2+3);
document.write("(1+2)>=(2+3):"+larger+"<br/>");
var larger=(1+2)<=(2+3);
document.write("(1+2)<=(2+3):"+larger+"<br/>");
var larger=(1+2)==(2+3);
document.write("(1+2)==4:"+larger+"<br/>");
var larger=(1+2)!=(2+3);
document.write("(1+2)!=4:"+larger+"<br/>");
var intersection=true&&(1>2);
document.write("ture&&(1>2):"+intersection+"<br/>");
var union=true||(1>2);
document.write("ture||(1>2):"+intersection+"<br/>");
var not=!(1>2);
document.write("!(1>2):"+intersection+"<br/>");
var a = Number("2018") + 1000;
document.write(a+"<br/>");
document.write("---------"+"<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("parseInt('+123')：" + parseInt("+123") + "<br/>");
document.write("parseInt('-123')：" + parseInt("-123"));
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/>");
var a = 2018 + "";
var b = a + 1000;
document.write(b+"<br/>");
var a = 2018;
var b = a.toString() + 1000;
document.write(b+"<br/>");
</script>
</body>
</html>