JavaScript 数据类型
字符串（String）、数字(Number)、布尔(Boolean)、数组(Array)、对象(Object)、空（Null）、未定义（Undefined）。
<!DOCTYPE html>
<html>
<body>
<script>
var person={
firstname : "John",
lastname : "Doe",
id : 5566
};
document.write(person.lastname + "<br>");
document.write(person["lastname"] + "<br>");
</script>
</body>
</html>
<script>
var i;
var cars = new Array();
cars[0] = "Saab";
cars[1] = "Volvo";
cars[2] = "BMW";
for (i=0;i<cars.length;i++)
{
document.write(cars[i] + "<br>");
}
</script>
var carname=new String;
var x= new Number;
var y= new
Boolean;
var cars= new Array;
var person= new Object;
var x= new Number;
var y= new
Boolean;
var cars= new Array;
var person= new Object;