How do brackets work in JavaScript import syntax to import both default and named exports?

Understanding Brackets in JavaScript Import Syntax

In JavaScript, the import syntax using brackets offers a flexible way to handle both default and named exports from a module. Let's examine its usage and implications.

Default vs. Named Exports

By convention, modules usually expose a single default export or a collection of named exports. A default export is assigned to a variable without braces, while named exports require explicit braces to enclose the exported symbols.

Importing with Brackets

When using brackets in an import statement, you are essentially combining both default and named export import methods. For example, the following syntax:

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

imports the default export React under the same name, while also importing named exports Component and PropTypes under their original names.

Simplified Syntax

This method combines the two common syntaxes:

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

where the first line imports the default export, and the second line imports named exports.

Module Export Structures

Typically, modules provide either a default export or a set of named exports. However, occasionally, a module may provide both. In such cases, the syntax using brackets allows you to import both types of exports simultaneously.

Comparison to MDN Documentation

Previous versions of MDN documentation incorrectly claimed that importing with brackets creates an object that receives imported values under the specified name. This is not the case. Braces explicitly import named exports, including default exports, if any.

Important Notes

• Named exports cannot be accessed via the default export.
• The * wildcard operator can import all named exports into a single object, while the default keyword can import the default export separately.

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