If I have the following HTML:

<div id="container">
  <iframe></iframe>
</div>

What is the most effective way (mainly in terms of performance) to create a reference to the <iframe> DOM element? I'm using something like the following:

var element = document.getElementById('container').getElementsByTagName('iframe')[0];

IIRC, though, getElementsByTagName can be a slow performer. Is that not an issue since there's only one element within the <div id="container"> anyway?

Is there a more concise, and/or better-performing way to get the <iframe> here? It's safe to say that it will always be the only child of <div id="container">, but not always the only <iframe> on the page.

Put an ID on the iframe and reference it with gEBI. If you're not noticing any latency with gEBTN then I suggest keeping the code the same as is, and yes providing a context for gEBTN helps.

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