<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Number</title>
<script type="text/javascript">
/*
在JS中所有的数值都是Number类型，
包括整数和浮点数（小数）
*/
var a = 123;//number
var b = '123';//string
// console.log(typeof b);
a = Number.MAX_VALUE;//1.7976931348623157e+308
a = Number.MAX_VALUE*Number.MAX_VALUE;//Infinity正无穷
a = Infinity;//number
a = 'abc' * 'bcd'; //NaN(Not a Number)不是一个数字
a = NaN;//number
a = 'NaN';//string
a = Number.MIN_VALUE;//5e-324
// console.log(typeof a);
var c = 123 + 456
c = 0.1 + 0.2;//0.3000000000004
// console.log(c)
var f = 0.1;
var g = 0.2;
console.log(f + g);
console.log((parseFloat(f)*1000 + parseFloat(g)*1000) / 1000);//0.3
</script>
</head>
<body>
</body>
</html>
