Question

Does anyone know how to detect if the iframe sandbox attribute is supported by the browser without relaying on version checks, etc?

Answer 1

You can check whether an iframe element has the sandbox attribute:

var sandboxSupported = "sandbox" in document.createElement("iframe");

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Side note

A good way to find feature detects is to look at Modernizr and see if it has one already. This is the Modernizr code for the sandbox attribute test:

Modernizr.addTest('sandbox', 'sandbox' in document.createElement('iframe'));

Alternatively (if you need to use lots of feature detects in your app) include Modernizr and use it properly, instead of just getting ideas from its source!