In your case it is telling you that you’re using a variable without defining it. This could be a potential bug. The lint tool doesn't know that you're importing jQuery and that jQuery makes a global variable called available.
The tool is telling you how to fix this warning. Either there’s a bug in your code (using a variable that doesn’t exist) or you’re using a global variable (what you’re doing). Solution is to put the comment from the tooltip at the top of your file:
/* global $ */
While it seems annoying, consider that such tools are widely used across the industry to check for potential bugs. They are very helpful to increase code quality and are incorporate in many build processes.
It is also helpful for others who work with your code. They immediately see at the top of the file what global variables you assume to be available when you run the code.