Many JavaScript functions can be replaced with jQuery methods, but there are still many JavaScript functions that need to be used for specific tasks. Note that is not required to have the jQuery core file loaded in the <head> scetion for JavaScript commands to work. All modern browsers recognize JavaScript commands. They do need to be placed inside of <script type="text/javascript">...</script> tags inside the HTML document for the browser to recognize them as JavaScript commands. You should also note that if the user's browser has disabled JavaScript, the commands will not function. 

You can use JavaScript commands right along side jQuery methods, as jQuery is written in JavaScript.

Following is a list of articles on some of the more commonly used JavaScript functions and properties.

retrieves the element with the specified id

retrieves all elements in the document with the specified class

returns or assigns the HTML content of the specified element

cancels the default action from occuring

will return value of a string in all lower case characters

will return value of a string in all upper case characters

envokes a popup dialog box with specified content

allows you to retrieve local date and time information

writes the content of the parentheses into the open HTML document

returns true if a value is NOT a number

takes the value of a string and returns it as a number if possible