Why use Braces in JavaScript Import Syntax?

Using Brackets with JavaScript Import Syntax

The JavaScript import syntax allows for the importation of libraries and modules. A recently encountered library uses the following syntax:

import React, { Component, PropTypes } from 'react';

This syntax differs from the more conventional technique, which is to import React without braces:

import React, Component, PropTypes from 'react';

Understanding the Syntax with Braces

The syntax with braces indicates that the default export from 'react' should be imported under the name React. Additionally, the named exports Component and PropTypes should be imported under the same names. This is a combination of the two common syntaxes:

import React from 'react';
import { Component, PropTypes } from 'react';

Purpose of the Brace Syntax

In general, most modules provide either a single default export or a list of named exports. It is uncommon for modules to offer both. However, when a module has a common feature exported as a default and additional sub-features, the brace syntax can be used. This syntax allows for the ideal feature to be imported as the default, while the others are named exports.

Alternative Explanations

To further clarify, the brace syntax is equivalent to:

import { default as React, Component, PropTypes } from 'react';

This indicates that the default export from 'react' is being imported as React and the named exports Component and PropTypes are also being imported as themselves.

On the other hand, the syntax without braces is equivalent to importing the default export of 'react' as React while also importing the named exports Component and PropTypes.

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