1) Check to see that you are working on the right files
It’s easy to mix up the files on your local machine with those on the server, or the scripts.js file in one folder with the scripts.js from a previous project. If you are making lots of changes and none of them are showing up on your site, you might be editing the wrong file.
2) Check to make sure all files are loading
3) Check to make sure you aren’t loading duplicate files/libraries
Look at each of the script links in your HTML file to see if any are pointing to files with similar names. For instance, if you are linking to a local version of jQuery and the version hosted on the Google Code website, your code will probably run into all sorts of conflicts. This typically happens when you start using a plugin that relies on jQuery and you just copy and paste their script links. Keep in mind that some libraries might be the same and have very different naming styles. For instance, in Google Code, the jQuery file name looks like “jquery.min.js”, but if you download a version with a plugin or from the jQuery website, it might look like “jquery-1.9.1.min.js”. All the same, linking to both of these files will mess up your code. Make sure you know and understand what each of your links are pointing to.
Any jQuery specific code should always appear INSIDE the main jQuery function.
5) Check to see if you have any errors
6) Make sure that the code you are using is being applied to the right elements
Double check that the selector (eg. $(‘selector’)) is referring the correct element. Are you selecting a div tag when you mean to select an item inside of it? Are you selecting all <a> tags when you just mean to select the <a> tags in your nave? Did you forget to put a period in front of your class name? Think about what you are trying to do before you start coding to make sure you know what your goals are.