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POHow to determine the extension's directory
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  1. POHow to determine the extension's directory
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    copied!<p>I need to get the path of the extension installed directory from JavaScript.</p> <p>My goal is to write to a JSON file within the extension directory from a Firefox extension. In order to do that, I need to determine the directory in which the extension is installed within the Firefox profile.</p> <p>I use this code: </p> <pre><code>function writeToFile() { var id = "plugin@uua";// The extension's id from install.rdf(i.e. &lt;em:id&gt;) var ext = Components.classes["@mozilla.org/extensions/manager;1"] .getService(Components.interfaces.nsIExtensionManager) .getInstallLocation(id) .getItemLocation(id); var file = Components.classes["@mozilla.org/file/local;1"] .createInstance(Components.interfaces.nsILocalFile); file.initWithPath(ext.path); file.append("config.json"); var foStream = Components.classes["@mozilla.org/network/file-output-stream;1"] .createInstance(Components.interfaces.nsIFileOutputStream); foStream.init(file, 0x02 | 0x08 | 0x20, 0666, 0); var data = '[ {"id" : "2"} ]'; foStream.write(data, data.length); foStream.close(); </code></pre> <p>It throws the following error: </p> <pre><code>TypeError:Components.classes['@mozilla.org/extensions/manager;1'] is undefined. </code></pre> <p><strong>I essentially need to get the path of the extension automatically from JavaScript.</strong> I double checked the ID of my extension and I also tried writing to files from other extensions with no luck.</p> <hr> <p>Thanks very much for your replies. It didn't let me solve my problem instantly anyway but it forced me to reading Mozilla documentation. I finally got a hang of how it works. Thanks again.</p> <p><strong>Solution to the question above:</strong> </p> <pre><code> Components.utils.import("resource://gre/modules/AddonManager.jsm"); Components.utils.import("resource://gre/modules/FileUtils.jsm"); AddonManager.getAddonByID("plugin_id", function(addon) { var uri = addon.getResourceURI("config.json"); var file = Components.classes["@mozilla.org/file/local;1"] .createInstance(Components.interfaces.nsILocalFile); var stringUri = uri.asciiSpec; stringUri = stringUri.replace(new RegExp(/\//g), '\\'); stringUri = stringUri.slice(8); alert(stringUri); file.initWithPath(stringUri); alert(addon.hasResource("config.json")); var stream = FileUtils.openFileOutputStream(file, FileUtils.MODE_WRONLY | FileUtils.MODE_CREATE | FileUtils.MODE_TRUNCATE); stream.write(dataToWrite, dataToWrite.length); stream.close(); </code></pre>
 

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