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PO'Date' is undefined in IE9 in javascript loaded by FacePile
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copied!<p>I'm currently getting an error within Facebook's FacePile code, and I'm baffled by the cause.</p> <p>facepile.php loads a script which, among other things, has these lines (when pretty-printed):</p> <pre class="lang-js prettyprint-override"><code>... o = document.createElement('script'); o.src = l[n]; o.async = true; o.onload = h; o.onreadystatechange = function() { if (o.readyState in c) { h(); o.onreadystatechange = null; } }; d++; a.appendChild(o); ... </code></pre> <p>(a == document.body, d++ is irrelevant here)</p> <p>This code loads a script with src = <code>http://static.ak.fbcdn.net/rsrc.php/v1/yW/r/pmR8u_Z_9_0.js</code> or something equally cryptic (the filename changes occasionally).</p> <p>In that script, there are these lines at the very top (also when pretty-printed):</p> <pre class="lang-js prettyprint-override"><code> /*1331654128,176820664*/ if (window.CavalryLogger) { CavalryLogger.start_js(["\/8f24"]); } window.__DEV__ = window.__DEV__ || 0; if (!window.skipDomainLower && document.domain.toLowerCase().match(/(^|\.)facebook\..*/)) document.domain = window.location.hostname.replace(/^.*(facebook\..*)$/i, '$1'); function bagofholding() { } function bagof(a) { return function() { return a; }; } if (!Date.now) Date.now = function now() { return new Date().getTime(); }; if (!Array.isArray) Array.isArray = function(a) { return Object.prototype.toString.call(a) == '[object Array]'; }; ... </code></pre> <p>And I'm getting an error which says "SCRIPT5009: 'Date' is undefined", right at the <code>if (!Date.now)</code> portion. Debugging near that point reveals that <code>Date</code>, <code>Array</code>, <code>Object</code>, <code>Function</code>, etc are all undefined.</p> <p>Er... how? <code>window</code> exists, as does <code>document</code> (though <code>document.body</code> is null) and a handful of others, but plenty of pre-defined objects aren't. Earlier versions of IE don't seem to have this problem, nor do any other browsers, but multiple machines running IE9 (including a clean VM) all have the same issue.</p> <p>I doubt I can do anything about it, but I'm <em>very</em> curious how this is happening / what the underlying problem is. Does anyone know, or can they point me to something that might help?</p> <p>-- edit:</p> <p>Prior to posting this question, I had found this site: <a href="http://www.guypo.com/technical/ies-premature-execution-problem/" rel="nofollow noreferrer">http://www.guypo.com/technical/ies-premature-execution-problem/</a></p> <p>While it seemed (and still does) like it might be the source of the problem, I can't replicate it under any smaller circumstances. All combinations I've tried still have Date, etc defined ; which isn't too surprising, as otherwise I'm sure others would be seeing many more problems with IE.</p>

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