'$ is not defined' in code following jQuery include - javascript

I'm getting the familiar '$ is not defined' error in my JavaScript for the following line in one of my javascript files...
$(document).ready(function() { … }
Normally this is because I've forgotten to include jQuery, but not this time! I have included it, and it is the first include in the page. This error happens in included JavaScript files, and also in any code within tags, all of which come after the jQuery include. It also doesn't happen all the time, maybe half the time when I refresh the page.
I've also used jQuery quite a lot and never seen this before, so I am quite confused.
Edit:
Looking at the Net tab in Firebug, jQuery is being requested and I get a 200 response but nothing is sent back in the response body. If I open the file directly in a new tab or whatever, I get an empty document. Firefox seems to think the file is cached but the data size is 0. Cache control is 'no-cache'. Confused.
Edit 2:
Opened jQuery file in VisualStudio, saved jQuery file with no modifications, everything works perfectly now. Still totally confused.

Are you sure that jQuery is actually being loaded into the browser? It sounds like it really isn't. You should use Firebug or Fiddler to check all the http requests to see if it is actually being downloaded.
Here's a screenshot of how you can check this using Firebug.

Are you using Wordpress or some sort of CMS? If so, their version of jQuery may have of code at the end which calls jQuery.noConflict(). You can read about this method here: http://api.jquery.com/jQuery.noConflict/
This means that whenever you want to use the $ function, you need to use jQuery instead.
For example...
Instead of
$("p").addClass("awesome");
You would do
jQuery("p").addClass("awesome").

Related

How can I debug this JavaScript error?

I have been asked to fix an issue with a website and I am encountering an issue with a JavaScript error.
On the home page, [removed website link], I am receiving the error Uncaught TypeError: undefined is not a function. However, the function being called on that line (line 30) should exist, as the jQuery plugin is being loaded.
The call-stack just shows a series of anonymous functions pointing towards the jQuery file. I am having trouble determining why this is producing an undefined function error.
I have tried using the Chrome debugger to step through the code where the error occurs but it just seems to highlight the jQuery source file for every step.
My question is this:
How do I go about tracking down the source of the issue when the trail is just a series of anonymous functions in the jQuery source file?
Is there something I am missing here or that I am not considering?
Thank you.
Edit:
As is it not clear, the method being called, jQuery.ContentSlider is in fact being included within the page within the file testimonials.js.
This is not just a "What's wrong with my code" question, but also an inquiry into how I handle situations such as this in the context of JavaScript & jQuery specifically.
A call stack of anonymous functions is confusing to me, and I have already attempted to take the obvious steps, such as verifying the plugin is included and that this inclusion takes place before attempting to utilize that plugin.
Sorry for the confusion.
Edit - Solution Found
It appears that although jQuery and the plugin were included prior to use, another copy of the same jQuery file was being injected by a Joomla! module. Since this was the exact same Google hosted jQuery file, it did NOT appear twice in the Resources tab in the Chrome Developer Tools. It appears that Chrome will parse jQuery twice, but doesn't show it as being included twice. So, the version with the plugin attached was being overwritten.
Thank you to those who answered. Thanks to A. Wolff for bringing that piece of information about the Resource tab to my attention.
You're loading the slider after you instantiate it.
Reverse the order of these two blocks:
<script type="text/javascript">
$(function() {
jQuery('#two').ContentSlider({
width : '440px',
height : '240px',
speed : 400,
easing : 'easeOutQuad',
textResize : true
});
});
</script>
<script src="/templates/sp/javascript/jquery.sudoSlider.min.js"></script>
Edit: To the heart of your well-formed question about debugging, generally, Undefined is not a function, especially when dealing with frameworks, is a symptom of trying to access a method before it exists, which is why your attempted function call returns undefined rather than a function.
It's almost always the result of loading a framework after trying to call it, or in an asynchronous context, of not waiting for the framework to load or do something important.
EDIT 2: The above answer is not correct, as A.Wolff points out: it's not that you must reverse the order of the two blocks, but that:
1) The second framework is probably not the one you want, or
2) You have called jQuery('#two').ContentSlider when you meant to call .sudoSlider, (or whatever is appropriate for that framework).

Export Flash parameters to JavaScript

I'm trying to pass parameters from Flash (as 3.0) to JavaScript.
Tried all methods I found in via. Google, as:
ExternalInterface.addCallback ("fonts", recieveFromJS);
Always one and the same problem; when I try to call the fonts () swfobject, JavaScript gives the error that the method doesn't exist.
Assuming your javascript code does not have a syntax error somewhere, this usually happens because of jquery (or some other js bundle) is stepping on your code. Try using a test page with just the javascript you need, removing all other code and header entries. If it works, then add scripts and links back, one at a time, and you will find which code is breaking it. If it does not work even in your test page, then you have a code/syntax/logic problem with the snippet of code you are working with. If you still have a problem with a code snippet, post it here and I or someone will surely help debug it for you.

Javascript plug-in doesnt appear on drupal

i want to put a soundcloud music player (http://stratus.sc/) on my drupalgardens page. i added an external source javascript library and uploaded a js file on the system as it says on the pluging website. all this tru the administration website of drupalgardens. When i check the sourcecode of my webpage it appears like the pluging is on the header. But it doesnt work, i cant see it. i activated all the jquery functions.
bit of sourcecode on header where the pluging seems there:
<script type="text/javascript" src="http://stratus.sc/stratus.js"></script>
<script type="text/javascript" src="http://NAMEOFMYSITE/sites/NAMEOFMYSITE/files/js/js_PRNQJr2GPf-FrbaSuV5IDQ1l6Lfby6e79KpPOUTf5kI.js"></script>
link:
http://bit.ly/10nyAHV
Any suggestions?
Note : The player im talking about is NOT the one that can be seen under the rotating banner. the one im talking about its supposed to be globally on the webpage at its seem on the pluging oficcial webpage
For one you're getting this console error: "Uncaught SyntaxError: Unexpected token < "
Not sure how that script is getting added but just removing the script tags may clear it up.
Even if the frame errors mentioned by KG are unrelated, you have to go clean that all up.
Your script should also be loaded after jquery. Since it looks like you have js aggregation turned on, I don't really know how to determine if drupal is loading things correctly. You can just tell your script to load in the footer instead of header if you're unsure. The links below explain how to do that.
Here are some javascript related resources for Drupal. They sometimes expect things to be handled differently.
The plugin is dependent on jQuery. By default, Drupal 7 loads jQuery 1.4. You may need to use the jQuery Update plugin to use 1.5, 1.7 or 1.8
Drupal Community docs about javascript:
http://drupal.org/node/756722
Drupal javascript API:
http://drupal.org/node/751744
I had a similar issue. Some reasons for a not working player are:
For some reason $ is not known (although jQuery is included). I replaced '$' by 'jQuery' and everything worked fine. That means use jquery(document).ready(... instead of $(document).ready(... and jQuery.stratus({.. instead of $.stratus({...
There is a typo on the stratos.sc web site. It should read $.stratus not $stratus (or jQuery.stratus, see previous hint).
Check that the source stratus.js and the initialisation code is included.
Mixture of https and http might be a good guess as reason for problems, but actually it works (I just tried it). If you can't find the problem, try to use a JavaScript debugger and check the error logs first!

Programatically retrieve count of javascript errors on page

I'd like to write a test case (using Selenium, but not the point of this question) to validate that my web application has no script errors\warnings or unhanded exceptions at certain points in time (like after initializing a major library).
This information can easily be seen in the debug consoles of most browsers. Is it possible to execute a javascript statement to get this information programatically?
It's okay if it's different for each browser, I can deal with that.
not so far read about your issue (as far as I understood your problem) here
The idea be the following:
I found, however, that I was often getting JavaScript errors when the page first loaded (because I was working on the JS and was introducing errors), so I was looking for a quick way to add an assert to my test to check whether any JS errors occurred. After some Googling I came to the conclusion that there is nothing built into Selenium to support this, but there are a number of hacks that can be used to accomplish it. I'm going to describe one of them here. Let me state again, for the record, that this is pretty hacky. I'd love to hear from others who may have better solutions.
I simply add a script to my page that will catch any JS errors by intercepting the window.onerror event:
<script type="text/javascript">
window.onerror=function(msg){
$("body").attr("JSError",msg);
}
</script>
This will cause an attribute called JSError with a value corresponding to the JavaScript error message to be added to the body tag of my document if a JavaScript error occurs. Note that I'm using jQuery to do this, so this specific example won't work if jQuery fails to load. Then, in my Selenium test, I just use the command assertElementNotPresent with a target of //body[#JSError]. Now, if any JavaScript errors occur on the page my test will fail and I'll know I have to address them first. If, for some strange reason, I want to check for a particular JavaScript error, I could use the assertElementPresent command with a target of //body[#JSError='the error message'].
Hope this fresh idea helps you :)
try {
//code
} catch(exception) {
//send ajax request: exception.message, exception.stack, etc.
}
More info - MDN Documentation

How to help the debugger see my javascript, or how to best refactor my script to help make it debugger-friendly?

I have an ASP.NET MVC project that uses some simple AJAX functionality through jQuery's $.get method like so:
$.get(myUrl, null, function(result) {
$('#myselector').html(result);
});
The amount of content is relatively low here -- usually a single div with a short blurb of text. Sometimes, however, I am also injecting some javascript into the page. At some point when I dynamically include script into content that was itself dynamically added to the page, the script still runs, but it ceases to be available to the debugger. In VS2008, any breakpoints are ignored, and when I use the "debugger" statement, I get a messagebox saying that "no source code is available at this location." This fails both for the VS2008 debugger and the Firebug debugger in Firefox. I have tried both including the script inline in my dynamic content and also referencing a separate js file from this dynamic content -- both ways seemed to result in script that's unavailable to the debugger.
So, my question is twofold:
Is there any way to help the debugger recognize the existence of this script?
If not, what's the best way to include scripts that are used infrequently and in dynamically generated content in a way that is accessible to the debuggers?
I can not comment yet, but I can maybe help answer. As qwerty said, firefox console can be the way to go. I'd recommend going full bar and getting firebug. It hasn't ever missed code in my 3 years using it.
You could also change the way the injected javascript is added and see if that effects the debugger you're using. (I take it you're using Microsoft's IDE?).
In any case, I find the best way to inject javascript for IE is to put it as an appendChild in the head. In the case that isn't viable, the eval function (I hate using it as much as you do) can be used. Here is my AJAX IE fixer code I use. I use it for safari too since it has similar behavior. If you need that too just change the browser condition check (document.all for IE, Safari is navigator.userAgent.toLowerCase() == 'safari';).
function execajaxscripts(obj){
if(document.all){
var scripts = obj.getElementsByTagName('script');
for(var i=0; i<scripts.length; i++){
eval(scripts[i].innerHTML);
}
}
}
I've never used jquery, I preferred prototype then dojo but... I take it that it would look something like this:
$.get(myUrl, null, function(result) {
$('#myselector').html(result);
execajaxscripts(result);
});
The one problem is, eval debug errors may not be caught since it creates another instance of the interpreter. But it is worth trying.. and otherwise. Use a different debugger :D
This might be a long shot, but I don't have access to IE right now to test.
Try naming the anonymous function, e.g.:
$.get(myUrl, null, function anon_temp1(result) {
$('#myselector').html(result);
});
I'm surprised firebug is not catching the 'debugger' statement. I've never had any problems no matter how complicated the JS including method was
If this is javascript embedded within dynmically generated HTML, I can see where that might be a problem since the debugger would not see it in the initial load. I am surprised that you could put it into a seperate .js file and the debugger still failed to see the function.
It seems you could define a function in a seperate static file, nominally "get_and_show" (or whatever, possibly nested in a namespace of sorts) with a parameter of myUrl, and then call the function from the HTML. Why won't that trip the breakpoint (did you try something like this -- the question is unclear as to whether the reference to the .js in the dynamic HTML was just a func call, or the actual script/load reference as well)? Be sure to first load the external script file from a "hard coded" reference in the HTML file? (view source on roboprogs.com/index.html -- loads .js files, then runs a text insertion func)
We use firebug for debug javascript, profile requests, throw logs, etc.
You can download from http://getfirebug.com/
If firebug don't show your javascript source, post some url to test your example case.
I hope I've been of any help!
If you add // # sourceURL=foo.js to the end of the script that you're injecting then it should show up in the list of scripts in firebug and webkit inspector.
jQuery could be patched to do this automatically, but the ticket was rejected.
Here's a related question: Is possible to debug dynamic loading JavaScript by some debugger like WebKit, FireBug or IE8 Developer Tool?

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