Question

Sometimes I make a function and call the function later.

Example:

function example { alert('example'); }
example(); // <-- Then call it later

Somehow, some functions cannot be called. I have to call those functions inside:

$(function() { });

What do $(function() {}); and (function() { }); mean, and what’s the difference/purpose of these?

Answer 1

$(function() { ... });

is just jQuery short-hand for

$(document).ready(function() { ... });

What it’s designed to do (amongst other things) is ensure that your function is called once all the DOM elements of the page are ready to be used.

However, I don’t think that’s the problem you’re having – can you clarify what you mean by ‘Somehow, some functions are cannot be called and I have to call those function inside’ ?
Maybe post some code to show what’s not working as expected ?

Edit: Re-reading your question, it could be that your function is running before the page has finished loaded, and therefore won’t execute properly; putting it in $(function) would indeed fix that!