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Showing posts from April, 2014

Ajax File Uploads with JavaScript's File API

Developers have been using Ajax techniques for years to create dynamic web forms, but handling file uploads using Ajax was always problematic. The crux of the problem was security – it's not a good idea to allow arbitrary code access to any file it wants on a user's system so JavaScript was intentionally restricted in how it could interact with things like file input elements. Uploading a file with JavaScript was essentially a standard form submission that targeted a hidden iframe. It felt dirty but it got the job done.The W3C began work on standardizing a File API for JavaScript sometime between 2006 and 2009 and we're now at the point with browser support where developers can take advantage of it. Developers supporting web apps on IE8 and 9 still need to use iframes, but those of us targeting newer browsers can finally take a pure JavaScript approach to file uploads. And as more users migrate from IE8/9, the iframe approach will eventually be left in the du…