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POHow Google Closure EventTarget works?
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copied!<p>I'm hitting an error in advanced compilation mode.</p> <pre><code>Uncaught TypeError: Object #<d> has no method 'attachEvent' </code></pre> <p>After some source map magic I figured that this is thrown from <code>goog.events.listen</code> call, where first argument is my custom object, inheriting <code>goog.events.EventTarget</code>.</p> <p>This is in closures's source</p> <pre><code>goog.events.EventTarget.prototype.addEventListener = function( type, handler, opt_capture, opt_handlerScope) { goog.events.listen(this, type, handler, opt_capture, opt_handlerScope); }; </code></pre> <p>So this function ends up on prototype of my object, along with <code>customEvent_ = true</code>, then in <code>goog.events.listen</code></p> <pre><code>// Attach the proxy through the browser's API if (src.addEventListener) { if (src == goog.global || !src.customEvent_) { src.addEventListener(type, proxy, capture); } } else { // The else above used to be else if (src.attachEvent) and then there was // another else statement that threw an exception warning the developer // they made a mistake. This resulted in an extra object allocation in IE6 // due to a wrapper object that had to be implemented around the element // and so was removed. src.attachEvent(goog.events.getOnString_(type), proxy); } </code></pre> <p>(The last line is the one that throws)</p> <p>Shouldn't this end up in stack overflow? Why is it going into <code>else</code> branch if my object inherits <code>addEventListener</code> from <code>EventTarget</code>? In simple compilation mode, everything works fine. How does this work, and why am I getting the error only in advanced compilation mode?</p>

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