What does the jQuery() function in jQuery do?

Question

In this video there is a snippet of code that goes something like this:

if (jQuery) {jQuery(function() {
    // ...
})}

I\'ve never seen the

Answer 1

$() is an alias for jQuery(), defined as:

// Expose jQuery to the global object
window.jQuery = window.$ = jQuery;

http://code.jquery.com/jquery-1.4.js

there is a special case defined when $() or jQuery() is called with the first argument being a function:

// HANDLE: $(function)
// Shortcut for document ready
} else if ( jQuery.isFunction( selector ) ) {
    return rootjQuery.ready( selector );
}

sometimes $ can conflict with other libraries (like prototype) that define the same function, so if you call

jQuery.noConflict();

it will remove the $ alias, setting it back to the original value found, essentially:

window.$ = _$;