Question

personally I prefer the first syntax

jQuery()

is it safe respect to the common used:

$(document).ready()

For the other selector i will anyway use $('#id'). i am just asking for the first .ready

Answer 1

The two names $ and jQuery are synonyms. jQuery is the more explicit; $ may be overridden if you use another framework.

If you pass a function as the first argument to your call to the jQuery function (or, obviously, to $), it is executed exactly as if it were a call to jQuery(document).ready. So yes, it is exactly the same.

Indeed, all these are functionally equivalent (provided you don’t have anything else mucking around with $):

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

It is entirely a matter of circumstance and style as to which you use.

My personal preference is to use the explicit $(document).ready call (#1): it is obvious that this is code that will be run when the DOM is ready. The major advantage of your preference (#4) is that it clearly denotes that the code is jQuery, which may be useful for someone reading your code in future.