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POLoading javascript asynchronously - How to do callbacks?
 

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    <p>I am building a javascript widget that should load asynchronously.</p> <p>Problem is that there can be more than 1 of these widgets on the page and that the widget should be initialized by sending it an option array via {}.</p> <p>What is the best way to accomplish this? I heard that simply setting onload or onreadystatechange does not work in all browsers. </p> <p>I've checked out the digg widget, but I can't really comprehend what they're doing, could anyone take a look at that? </p> <p>Here's some of their code:</p> <pre><code>(function () { var s, s1, diggWidget = { id: "digg-widget-1282651415272", width: 300, display: "tabbed" }; if (window.DiggWidget) { if (typeof DiggWidget == 'function') { new DiggWidget(diggWidget); } else { DiggWidget.push(diggWidget); } } else { DiggWidget = [diggWidget]; s = document.createElement('SCRIPT'); s.type = 'text/javascript'; s.async = true; s.src = 'http://widgets.digg.com/widgets.js'; s1 = document.getElementsByTagName('SCRIPT')[0]; s1.parentNode.insertBefore(s, s1); } })(); </code></pre> <p>So, if the DiggWidget is already available (loaded earlier due to multiple instances), it makes a new widget if DiggWidget is a function, otherwise DiggWidget is used as an array and the current settings are pushed to it. </p> <p>First, why would DiggWidget ever be a function?</p> <p>If the widget is the only one (or first), the script tag is added asynchronously, no callbacks are defined.</p> <p>Then, looking at widgets.js they do this:</p> <p>At the top: </p> <pre><code>(function () { var A; if (window.DiggWidget) { if (typeof DiggWidget != "function") { A = DiggWidget } else { return } } </code></pre> <p>At the bottom: </p> <pre><code> if (A) { while (A.length) { new DiggWidget(A.shift()) } } </code></pre> <p>Now I don't quite understand this. Is DiggWidget (the array) available to that .js ? It's in a anonymous function. So if I include such a script twice, wouldn't DiggWidget be a new instance every time? </p> <p>Or am I completely in the wrong on this? Sorry if so. If there's any better methods to have a callback with multiple instances of the script, please do tell.</p>
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