window.frames['myframe'] gives me an error in Firefox?

$(window.frames['myframe'].document.getElementById('frameid'))

This statement sometimes returns nu开发者_C百科ll in Firefox but working properly in any other browsers. What can be the problem ?

Thanks in advance,

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By the looks of it you simply need to change the selector it should be

$('#myframe').contents().find('#frameid').html();

JQuery handles the finding of it, take a look at selectors in jQuery Selectors