How does new wrapper work in JavaScript?

Question

In the context of underscore.js:

// Create a safe reference to the Underscore object for use below.
   var _ = function(obj) { return new wrapper(obj); };

Simply put, what does this function return?

it returns a new instance of the wrapper type. Read more about javascript's object model here: https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Details_of_the_Object_Model — Esailija, Aug 06 '12 at 21:27
Which is an object oriented bit of code, based on some other javascript you would likely have somewhere. That has the wrapper object/class in it. — chris, Aug 06 '12 at 21:28

score 1 · Accepted Answer · edited May 23 '17 at 12:27

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It is a wrapper function for the wrapper constructor to allow you using underscore without the new keyword. Calling underscore will always return a new wrapper instance.

Btw, the wrapper function has been removed in this commit. The _ function itself is the constructor now, see Understanding the declaration of the underscore in _.js? for explanation.

edited May 23 '17 at 12:27

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answered Aug 06 '12 at 22:24

Bergi

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score 0 · Answer 2 · answered Aug 06 '12 at 22:14

simply put, it's a constructor for 'wrapper' to make things a big easier for you

// this allows you to do things such as:
var a = _({/*object*/});

// rether than something like:
var a = new wrapper({/*object*/});

I think in the since of underscore.js it's to keep your coding tiddy and simple :)

How does new wrapper work in JavaScript?

2 Answers2