Curly brackets (braces) in Node.js 'require' statement

I am trying to understand the difference between the two 'require' statements below.

Specifically, what is the purpose of the `{ }`s wrapped around `ipcMain`?

const electron = require('electron')

const {ipcMain} = require('electron')

They both appear to assign the contents of the `electron` module, but they obviously function differently.

Can anyone shed some light?

With `const electron = require('electron')`, the `ipcMain` module will be available as `electron.ipcMain`.

With `const {ipcMain} = require('electron')` the `ipcMain` module will be available as `ipcMain`.

This construct is called [*object destructuring*][1] and achieves the same as the Python construct

from library import ...

In its basic form it allows you to refer to the properties of an object directly:

var o = {prop1: '1', prop2: 2}
var {prop1, prop2} = o
console.log(prop1) // '1' (same as o.prop1)
console.log(prop2) // 2 (same as o.prop2)

Check:

const {ipcMain} = require('electron')
const myElectron = require('electron')
const myipcMain = myElectron.ipcMain
console.log(myipcMain===ipcMain) // true

You can use the destructuring assignment to import multiple properties of a JavaScript object, e.g.:

const { app, BrowserWindow, ipcMain } = require('electron')

If you use a property that doesn't exist, this will be set to `undefined` and you won't get an error.

const {app, BrowserWindow, ipcMain, doesntExist} = require('electron')
console.log(doesntExist) // undefined

See also: *[What does curly brackets in the `var { … } = …` statements do?][2]*

[1]:

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[2]:

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The second example uses destructuring.

This will call the specific variable (including functions) that are exported from the required module.

For example (functions.js):

module.exports = {
func1,
func2
}

is included in your file:

const { func1, func2 } = require('./functions')

Now you can call them individually,

func1()
func2()

as opposed to:

const Functions = require('./functions')

are called using dot notation:

Functions.func1()
Functions.func2()

You can read about destructuring [here][1], it is a very useful part of ES6 and can be used with arrays as well as objects.


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