Why Need To Pass Jquery Object As Parameter To Closure?

To avoid global variables in JavaScript code I many times seen that people use this construct: (function($) { // here code // here code })(jQuery); So I have questions: wh

Solution 1:

You don't have to. You can name the function argument whatever you want it to be. It is just a common/best practice of people using jQuery since it is common to use $ as an alias to jQuery library object.

The reason why you should do it is because there are other libraries that use $ as an alias to their library objects. It is needed to avoid collisions with those libraries since function closure will ensure $ to be jQuery object inside the wrapper function.

Here's an example:

(function (myJqueryAlias) {
     console.log(myJqueryAlias('document') === jQuery('document'));
})(jQuery);

Solution 2:

With this you archive that in this block you still have $ as jQuery and you can still write stuff like "$("selector")" instead of "jQuery("selector")". And outside this block the variable $ is still what it should be (for example you use another JSLib that uses the $ too)