The documentation of some JavaScript APIs shows the following snippets as an example of how to invoke some function:

<button type=button onClick=foo.DoIt(72930)>Click</button>



<button type=button onClick=foo.DoIt(42342::37438)>Click</button>

:: is obviously used here to allow either one or two arguments to be passed to the function.

What does :: do in JavaScript?

And how does the function know if one or two values were passed? How does it read them?

On closer look, the examples show other weird stuff like

<button type=button onClick=foo.Bar(72//893)>Click</button>



<button type=button onClick=foo.Qux(425;1,34::)>Click</button>

At least the // looks just wrong.

So I guess it's not some fancy new syntax that I'm not aware of, but maybe the examples are just missing quotes around a single string argument.