<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript">
//String()数字类转为字符串型
var a1=12345
var b1=typeof String(a1)
document.write(b1,"<br>")
//Number()字符串转为数字类型
var a2="12345"
var b2=typeof Number(a2)
document.write(b2,"<br>")
//Boolean()字符串转为布尔型
var a3=12345
var b3=typeof Boolean(a3)
document.write(b3,"<br>")
//parseInt()字符串转为整型
var a4="12345"
var b4=typeof parseInt(a4)
document.write(b4,"<br>")
</script>
</head>
<body>
</body>
</html>