@martinrinehart said:

What does void(0) do?

The void operator evaluates the given expression and then returns undefined. If you have pass 0 as the unary expression operand to the void operator, JavaScript coerces 0 to "false" and returns, but void doesn't care and simply returns undefined, which means "do nothing" . Put them together and you have composed a way to programmatically "do nothing" when a link is clicked. JavaScript Void(0) is often used when, inserting an expression into a web page may produce an unwanted side-effect.