For/In 循环
JavaScript for/in 语句循环遍历对象的属性:
var person={fname:"John",lname:"Doe",age:25}; for (x in person) { txt=txt + person[x]; }
in
for (var i=0,len=cars.length; i<len; i++) { document.write(cars[i] + "<br>"); }
var i=0,len=cars.length;