How can you check if your document is opened in an IFrame?

Is there a way to know if your page is opened inside of an IFrame?

An idea I had was to see if the window object has a .parent property, but this apparently is also true of standalone windows which are opened by Javascri开发者_JAVA百科pt's window.open() function.

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if (window.top != window.self)
 {
}