Question

This function declaration doesn’t make sense to me. What does the $ sign do?

function $(id) { return document.getElementById(id); }  

Also, this code is interfering with other Javascript code. If I comment it out, then the other Javascript code I’m trying to use works, but then I lose some other functionality.

Why might it be interfering with my other code.

Answer 1

You are declaring a function called $ that wraps document.getElementById, apparently for convenience. Nothing special.

Reference What characters are valid for JavaScript variable names?

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As for the interference, there is likely another global variable called $, which is being clobbered. See jQuery.