firefox - Why use var { VariableName } = require('') in javascript? - Stack Overflow

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I have seen lot of examples in Firefox addon-sdk which uses the below style when declaring a variable.

var { Hotkey } = require("sdk/hotkeys");

What difference it makes with var { Hotkey } than using var HotKey? Why the extra flower brackets are used?

I have seen lot of examples in Firefox addon-sdk which uses the below style when declaring a variable.

var { Hotkey } = require("sdk/hotkeys");

What difference it makes with var { Hotkey } than using var HotKey? Why the extra flower brackets are used?

• javascript
• firefox
• coding-style
• firefox-addon-sdk

Share Improve this question Follow asked Feb 13, 2013 at 7:14 Navaneeth K NNavaneeth K N 15.5k3838 gold badges132132 silver badges189189 bronze badges 1

• Don't know myself, but this might have some information for you: stackoverflow./questions/4445496/… – CodeMoose Commented Feb 13, 2013 at 7:19

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1 Answer 1

Sorted by: Reset to default 14

This is destructuring assignment.

var {Hotkey} = require('sdk/hotkeys');

is equivalent to:

var Hotkey = require('sdk/hotkeys').Hotkey;

See also the harmony:destructuring proposal, which includes the following examples:

// object destructuring
var { op: a, lhs: b, rhs: c } = getASTNode()

// digging deeper into an object
var { op: a, lhs: { op: b }, rhs: c } = getASTNode()

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