Export all functions from a file in JavaScript

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Borislav Hadzhiev

Last updated: Mar 29, 2022

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Export all functions from a file in JavaScript #

Use named exports to export all functions from a file, e.g. export function A() {} and export function B() {}. The exported functions can be imported by using a named import as import {A, B} from './another-file.js'. You can have as many named exports as necessary in a file.

Here is an example of exporting all of the functions from a file called another-file.js.

another-file.js
// 👇️ named export export function sum(a, b) { return a + b; } // 👇️ named export export const multiply = (a, b) => { return a * b; };

Note that using export on the same line as the function's definition is the same as exporting the functions as an object after they have been declared.

another-file.js
function sum(a, b) { return a + b; } const multiply = (a, b) => { return a * b; }; // 👇️ named exports (same as previous snippet) export {sum, multiply};

Here is how we would import the functions in a file called index.js.

index.js
import {sum, multiply} from './another-file.js'; console.log(sum(50, 50)); // 👉️ 100 console.log(multiply(50, 50)); // 👉️ 2500

Make sure to correct the path that points to the another-file.js module if you have to. The example above assumes that another-file.js and index.js are located in the same directory.

For example, if you were importing from one directory up, you would do import {sum, multiply} from '../another-file.js'.

We wrapped the names of the functions in curly braces when importing them - this is called a named import.

You can also import all of functions as properties of an object, using the module object pattern.

index.js
import * as myObj from './another-file.js'; console.log(myObj.sum(50, 50)); // 👉️ 100 console.log(myObj.multiply(50, 50)); // 👉️ 2500

The import/export syntax is called ES6 Modules in JavaScript.

In order to be able to import a function from a different file, it has to be exported using a named or default export.

The example above uses named exports and named imports.

The main difference between named and default exports and imports is - you can have multiple named exports per file, but you can only have a single default export.

If you try to use multiple default exports in a single file, you would get an error.

another-file.js
export default function sum(a, b) { return a + b; } const multiply = (a, b) => { return a * b; }; // ⛔️ SyntaxError: Duplicate export of 'default' export default multiply;

IMPORTANT: If you are exporting a variable (or an arrow function) as a default export, you have to declare it on 1 line and export it on the next. You can't declare and default export a variable on the same line.

Having said that, you can use 1 default export and as many named exports as you need in a single file.

Let's look at an example that exports multiple functions and uses both - default and named exports.

another-file.js
// 👇️ default export export default function sum(a, b) { return a + b; } // 👇️ named export export const multiply = (a, b) => { return a * b; };

And here is how you would import the two functions.

index.js
// 👇️ default and named imports import sum, {multiply} from './another-file.js'; console.log(sum(50, 50)); // 👉️ 100 console.log(multiply(50, 50)); // 👉️ 2500

Notice that we didn't wrap the default import in curly braces.

We used a default import to import the sum function and a named import to import the multiply function.

Note that you can only have a single default export per file, but you can have as many named exports as necessary.

In my experience, most real world codebases exclusively use named exports and imports because they make it easier to leverage your IDE for autocompletion and auto-imports.

You also don't have to think about which members are exported with a default or named export.

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