Wrapping or not within a function with JavaScript or jQuery

Question

Not very fluent in JavaScript or jQuery for front-end dev. Let's say I have this code:

$("#foo").click(function (event) {
    console.log("single click");
    return false;
});

$("#foo").dblclick(function (event) {
    console.log("double click");
    bar();
    return false;
});

function bar() { //do stuff };

But I've also seen it wrapped within a function:

$(function() {
    $("#foo").click(function (event) {
        console.log("single click");
        return false;
    });

    $("#foo").dblclick(function (event) {
        console.log("double click");
        return false;
    });

    function bar() { //do stuff };
});

Prototyping it, both seem to work. I guess that if they are wrapped within a function, it provides closure and may change things for scope a bit... However for a relative newb, are there pratical reasons why I might want (or not want) to systematically do one or the others? Is there a "better way" or is it rather "it depends", and if it depends... on what?