console
var number1=22;
var number2=33;
var myString="Heather";
var sum=number1+number2;
document.write(sum+"<br/>");
var sumString=number1+myString;
document.write(sumString+"<br/>");
var stringSum=myString+number2;
document.write(stringSum+"<br/>");
var stringNum=number1+"";
var stringNumSum=stringNum+number2;
document.write(stringNumSum+"<br/>");
document.write('---------------------------------------------<br/>')
var left =1;
var right=2;
left += right;
document.write(left+"<br/>");
left -= right;
document.write(left+"<br/>");
left*= right;
document.write(left+"<br/>");
left/=right;
document.write(left+"<br/>");
document.write('---------------------------------------------<br/>')
left=(1+2)+3;
right=(3+4)+1;
document.write((left>right)+"<br/>");
document.write((left<right)+"<br/>");
document.write((left>=right)+"<br/>");
document.write((left<=right)+"<br/>");
document.write((left==right)+"<br/>");
document.write((left!=right)+"<br/>");
document.write('---------------------------------------------<br/>')
var logicOperation = false;
logicOperation=(left>right) && (left<right);
document.write(logicOperation+"<br/>")
logicOperation=true && (left<right);
document.write(logicOperation+"<br/>")
logicOperation=(left>right) || (left<right);
document.write(logicOperation+"<br/>")
logicOperation=(left>right) || false;
document.write(logicOperation+"<br/>")
logicOperation=!(left>right);
document.write(logicOperation+"<br/>")
logicOperation=!(left<right);
document.write(logicOperation+"<br/>")
document.write('---------------------------------------------<br/>')
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('---------------------------------------------<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('---------------------------------------------<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/>')
var result=(2<1)?"小红":"小美";
document.write(result);
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<script>
var b= 10;
var a;
var myString = 'Heather';
var noSpace = null;
var isReal =true;
document.write(b + '<br/>');
document.write(a + '<br/>');
document.write(myString + '<br/>');
document.write(noSpace + '<br/>');
document.write(isReal + '<br/>');
</script>
</head>
<body>
</body>
</html>