how to judge a page is in a iframe use javascript?

Question

i use javascript to judge a page is in a iframe:

if (this != top) {
 alert("true");
}

enter image description here

but i get "true" all the time,even if not in a iframe(as up picture),who can help me?

• Pointy: An old question of possible interest.
• Surreal Dreams: Or possibly this.

Answer 1

Try

if (self != top) {
 alert("true");
}