js中for循环的多种方式

For/In 循环

JavaScript for/in 语句循环遍历对象的属性：

实例

var person={fname:"John",lname:"Doe",age:25};

for (x in person)
  {
  txt=txt + person[x];
  }

实例:

for (var i=0,len=cars.length; i<len; i++)
{
document.write(cars[i] + "<br>");
}