for in在对象和数组中的应用

var obj = {
    name:'lei',
    be:'dd',
    age:23
}
for(var poo in obj){
    alert('对象的属性和值为:'+poo+':'+obj[poo]);
}

var arr = [12,454,'dafda','feagfag'];
for(var a in arr){
    alert('数组的下标以及值为：'+a+':'+arr[a]);
}