Can someone explain the dollar sign in Javascript?

A '$' in a variable means nothing special to the interpreter, much like an underscore.

From what I've seen, many people using jQuery (which is what your example code looks like to me) tend to prefix variables that contain a jQuery object with a $ so that they are easily identified and not mixed up with, say, integers.

The dollar sign function $() in jQuery is a library function that is frequently used, so a short name is desirable.

In your example the $ has no special significance other than being a character of the name.

However, in ECMAScript 6 (ES6) the $ may represent a Template Literal

var user = 'Bob'
console.log(`We love ${user}.`); //Note backticks
// We love Bob.

The $ sign is an identifier for variables and functions.

https://web.archive.org/web/20160529121559/http://www.authenticsociety.com/blog/javascript_dollarsign

That has a clear explanation of what the dollar sign is for.

Here's an alternative explanation: http://www.vcarrer.com/2010/10/about-dollar-sign-in-javascript.html