Importing Modules in JavaScript: When Do Brackets Matter?

Exploring the Brackets in JavaScript Import Syntax

In JavaScript, importing modules is essential for structuring and organizing code. Two similar syntaxes for importing libraries are:

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

and

import React, Component, PropTypes from 'react';

The difference lies in the placement of brackets, which affects the interpretation of the import statement.

Method with Brackets:

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

This syntax specifies that React is the default export from the 'react' module and can be accessed directly as React. Component and PropTypes are named exports and must be accessed as React.Component and React.PropTypes.

This syntax combines the two common import styles:

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

Method without Brackets:

import React, Component, PropTypes from 'react';

This syntax assumes that React is the default export. However, Component and PropTypes are not considered named exports and cannot be accessed directly. Instead, they must be accessed as a property of the React object, e.g., React.Component, React.PropTypes.

Default Export vs Named Exports:

Typically, modules have a single default export or a list of named exports. A default export represents a module's core functionality, while named exports provide specific features. In the case of the 'react' module, its default export is the React library itself, while Component and PropTypes are named exports.

Practical Application:

For modules with both default and named exports, the syntax with brackets allows for a more concise and readable import statement. However, for modules with only a default export, the syntax without brackets is sufficient.

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