js變量類型：
1.字符串變量
<html lang="en">
<head>
<meta charset="UTF-8">
<title>1-變量類型</title>
</head>
<body>
<script>
//第一種字符串
username ='小金';
document.write('<h1>'+username+'</h1>')
</script>
</body>
</html>
2.整型
<html lang="en">
<head>
<meta charset="UTF-8">
<title>1-變量類型</title>
</head>
<body>
<script>
//第二種整型
//
username ='100';
alert(username-5);
</script>
</body>
</html>
3.浮點(diǎn)
3.141592627
4.布爾
fale true
<html lang="en">
<head>
<meta charset="UTF-8">
<title>1-變量類型</title>
</head>
<body>
<script>
//第二種布爾值
//
num = 67;
if(num>=60){
alert("及格");
}else{
alert('不及格');
}
</body>
</html>
5.數(shù)組
<html lang="en">
<head>
<meta charset="UTF-8">
<title>1-變量類型</title>
</head>
<body>
<script>
//數(shù)組
ps =['小金','小帥','小明','小東'];
alert(ps);
</script>
</body>
</html>
6.對(duì)象
JavaScript對(duì)象：
1.js對(duì)象
obj =new object();
<html lang="en">
<head>
<meta charset="UTF-8">
<title>1-變量類型</title>
</head>
<body>
<script>
obj = new Object();
obj.age = '20';
obj.name = 'xiaoming';
document.write('<h1>my age is '+ obj.age+'</h1>);
obj.say = function(){
alert(123);
}
</script>
</body>
</html>
2.dom對(duì)象
eleobjc = document;
7.json對(duì)象
<html lang="en">
<head>
<meta charset="UTF-8">
<title>1-變量類型</title>
</head>
<body>
<script>
jsobj = {'1':'22',
'2':'22'
'say':function(){
alert(123);
}
}
jsobj.say();
</script>
</body>
</html>
8.NaN 類型
# not a number
9.null 類型
# 一般用于提前規(guī)劃一些變量或給變量賦初值
str= null;
10.undefined 類型
#變量未定義
