Disclosure: I work for AgileBits, makers of 1Password.
For desktop browser extensions that are properly using the frameworks, the extension's Javascript runs in its own execution context so the page cannot redefine variables. This protected 1Password when we discovered that a certain page had redefined the global JSON object, which provides parse and stringify functions among other things, to be the number 3, i.e. a numeric constant called JSON. :'D
For desktop browser extensions that are properly using the frameworks, the extension's Javascript runs in its own execution context so the page cannot redefine variables. This protected 1Password when we discovered that a certain page had redefined the global JSON object, which provides parse and stringify functions among other things, to be the number 3, i.e. a numeric constant called JSON. :'D