javascript require("file") 和 require("file.js") 有什么区别？

Question

I have two files.

• import.js
• export.js

In import I do:

const export = require('export')

This will successful import the module from export.js. When I do require('export.js') (with file ending) it is also working.

So I was wondering what is the difference there? Is without slower?

Answer 1

Node.js automatically resolves some extensions. For example: .js, .json, etc. No, it works the same with or without the extension.

Answer 2

require in Node.js takes one argument which can be either module name or path. You can read for more info.

Answer 3

The difference between import/export and require is that require uses commonjs under the hood. While the import was introduced in ES6.

Even if you use ES6 import it's still transpiled into the commonjs . But using ES6 is recommended because with the time, it will be widely supported.

Performance-wise the difference will be negligible because the module files are evaluated only once but you will have to benchmark it, if you are very keen on the performance.