新的require（'下划线'）vs require（'下划线'）NodeJS [Webstorm 7自动完成]

Question

In some app.js, using the following code

var _ = require('underscore');

_.times(2, function() {
  console.log('Hello');
});

Webstorm 7 complains about unresolved function 'times'. After some googling I found out that if I do a var _ = new require('underscore'); then webstorm doesn't complain at all. However, I am very very new to NodeJS so couldn't grasp this properly.

Please tell me what is the difference between new require('') and require('') and how exactly it solved the issue. Also, are there performance implications of using new require ?

Answer 1

To make things clear: _ is a function, so you can use it with new keyword. But this is supposed to be used as wrapper, which adds methods to object you pass in order to make your api object oriented.

So if you use _ as a function or constructor you need to pass an object as an argument, and you'll get object with your data and some of underscore's functions attached as methods (that is, you don't need to pass your data as a first argument, it is incapsulated in object).

Basically, writing var _ = new require('underscore') is incorrect. You will get useless object, which definitely not real _ . And what about Webstorm - it will complain a lot, unless you turn these features off. Javascript is too dynamic to make them work in all cases.

Summary: use var _ = require('underscore'); , ignore Webstrom.