js遍历对象和遍历数组

var x;
var txt="";
var person={fname:"Bill",lname:"Gates",age:56};  //对象

for (x in person)
{
txt=txt + person[x]+"<br>";
}

var x;
var txt="";
cars=["BMW","Volvo","Saab","Ford"];  //数组
for (var x=0;x<cars.length;x++)
{
txt=txt+cars[x]+"<br>";
}