What side effects does the keyword 'new' have in JavaScript?

Question

I\'m working on a plug-in for jQuery and I\'m getting this JSLint error:

Problem at line 80 character 45: Do not use \'new\' for side effects.

(new jQuery.faste         


        

Answer 1

Travis, I am the developer behind the Starter site.

@Pointy hit the nail on the head. The reason the Starter code is written that way is because we do need a new object, we just don't need to store a reference to it at that point.

Simply changing the command from

(new jQuery.fasterTrim(this, options)); 

to

var fT = new jQuery.fasterTrim(this, options);

will appease JSLint as you have found.

The Starter plugin setup follows the jQuery UI pattern of storing a reference to the object in the data set for the element. So this is what is happening:

1. New object is created (via new)
2. The instance is attached to the DOM element using jQuery's data :$(el).data('FasterTrim', this)

There is no use for the object that is returned, and thus no var declaration made. I will look into changing the declaration and cleaning up the output to pass JSLint out of the box.

A little more background:

The benefit to storing the object using data is that we can access the object later at any time by calling: $("#your_selector").data('FasterTrim'). However, if your plugin does not need to be accessed mid stream that way (Meaning, it gets set up in a single call and offers no future interaction) then storing a reference is not needed.

Let me know if you need more info.