Question

I have a question regarding syntax that I’ve been coming across in JavaScript.

What does it mean if I define functions or variables inside a context like the one just below?
(source: http://tutorialzine.com/2010/12/better-confirm-box-jquery-css3/)

(function($) {
  $.confirm = function() {
   ...
  }

  $.confirm.hide = function() {
   ...
  }
})(jQuery);

Also, what the $. mean in the function $.confirm? Also, with $.confirm.hide, I feel that there is some jQuery object involved.

Answer 1

By wrapping a function in parens then executed using to more parents (function() {])(); is a n immediately invoked function. By passing in jQuery within the 2nd set of parens you pass in a paramter which you are you passing in as $.

$.confirm is just a method of the jQuery object

(function($) { // $ = jQuery
  $.confirm = function() {  // <-- set method of jQuery
   ...
  }


  $.confirm.hide = function() { // <-- set method of confirm
   ...
  }

   // usage
  $.confirm();
  // or
  jQuery.confirm();
})(jQuery); // pass in the jQuery object to the function via immediate invocation

Many libraries, like jQuery, use $ as a shortcut variable because it stands out from typical variables used in javascript.