What does return without any value mean in javascript?

Question

I always see a code like this but don't what the return statement is doing from here

function checkFileSize() {
var FS = document.getElementById("FS");
var files = FS.files;

// If there is (at least) one file selected
if (files.length > 0) {
if (files[0].size > 75 * 1024) { // Check the constraint
FS.setCustomValidity("The selected file must not be larger than 75 kB");
return;
}
}
// No custom constraint violation
FS.setCustomValidity("");
}

Answer 1

means quiting the function

Answer 2

Only returns the program flow/counter to the point just after function invocation.

Answer 3

Means return nothing....

Answer 4

Without value, wouldn't that mean 'undefined'?