referenceerror

I get a ReferenceError in the following userscript code: // ==UserScript== // @name ... // @namespace ... // @description ... // @include ... // @grant GM_xmlhttpRequest // ==/UserScript== console.log(GM_info); try { console.log(GM_xmlhttpRequest({ method: "GET", url: "http://google.ca/", synchronous: true }).readyState); } catch (e) { console.log(e); } ... It first logs GM_info successfully, then logs the ReferenceError. (I'm using Firefox/Firebug.) ReferenceError: GM_xmlhttpRequest is not defined Why do I get this error? I had the same problem, and what fixed it for me was adding this at the

In Chrome's JavaScript console, if I run this: var that = new XMLHttpRequest(); that.open('GET', 'http://this_is_a_bad_url.com', false); that.send(); I get an intentionally expected error: NetworkError: A network error occurred. I want to catch this, so I use: var that = new XMLHttpRequest(); that.open('GET', 'http://this_is_a_bad_url.com', false); try { that.send(); } catch(exception) { if(exception instanceof NetworkError) { console.log('There was a network error.'); } } However, I get an error about NetworkError not being defined: ReferenceError: NetworkError is not defined How can I catch

What's the differnce between TypeError: ... is undefined and ReferenceError: ... is not defined ? A ReferenceError occurs when you try to use a variable that doesn't exist at all. A TypeError occurs when the variable exists, but the operation you're trying to perform is not appropriate for the type of value it contains. In the case where the detailed message says "is not defined", this can occur if you have a variable whose value is the special undefined value, and you try to access a property of it. See http://javascriptweblog.wordpress.com/2010/08/16/understanding-undefined-and-preventing

Hi I am having a "Uncaught ReferenceError: $ is not defined" while using bellow codes I am currently getting the following error in my log. I have been looking at the samples in the framework and I just can't seem to find where the error is. It's been over a decade since I have done any HTML or js and what I did back then was very basic stuff. Any help would be appreciated <script type="text/javascript"> var sQuery = '<?php echo $sQuery; ?>'; $(document).ready(function(){ if($('input[name=sPattern]').val() == sQuery) { $('input[name=sPattern]').css('color', 'gray'); } $('input[name=sPattern]')

In Chrome and Firefox, typeof foo evalulates to 'undefined' . But typeof (function() { return foo; })() throws an error: ReferenceError: foo is not defined This destroys the notions that I have of susbstitutability of expressions! Until now, I knew of no conditions for which foo and (function() { return foo; })() are not the same. Is this standard behavior? If so, it would be helpful to quote the relevant part of the ECMAScript standard. EDIT: Another example: typeof (foo) typeof (foo + 0) I would have expect (foo) and (foo + 0) to throw an error. But the first one has no error; the second one