terser

library5.46.1jsnpmunverified

Terser is a powerful JavaScript parser, mangler, and compressor toolkit designed for modern ECMAScript (ES6+). It currently stands at version 5.46.1 and is under active development, serving as the maintained successor to the now-abandoned `uglify-es` project and `uglify-js` (which lacks ES6+ support). Terser largely retains API and CLI compatibility with its predecessors, making it a familiar choice for developers. Key differentiators include its robust support for modern JavaScript syntax and ongoing maintenance, addressing the limitations of older minifiers. While `terser` previously offered beautification features, these are being removed in favor of dedicated tools like Prettier. The project recommends using it in conjunction with bundlers like RollupJS for optimal output size.

serialization

npm install terser

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · TERSER

terser

serializationjavascriptv5.46.1

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

minify

✓ import { minify } from 'terser';

✗ const minify = require('terser').minify;

CommonJS users typically destructure `minify` from the `require` call. ES Modules use named import for this function.

MinifyOptions

✓ import type { MinifyOptions } from 'terser';

✗ import { MinifyOptions } from 'terser';

For TypeScript, use `import type` when importing only type definitions to ensure they are stripped during compilation and do not affect runtime.

All exports (namespace import)

✓ import * as Terser from 'terser';

✗ import Terser from 'terser';

Terser does not provide a default export. If you need to access multiple exports or prefer a namespace import, use `import * as Terser from 'terser';` and then access functions like `Terser.minify`.

Demonstrates how to programmatically minify a JavaScript string using `terser`, including compression and mangling options for ES2020 syntax.

import { minify } from 'terser'; const code = ` class Greeter { constructor(name) { this.name = name; } greet() { return 'Hello, ' + this.name + '!'; } } const greeter = new Greeter('World'); console.log(greeter.greet()); `; async function runMinification() { try { const result = await minify(code, { compress: { dead_code: true, drop_console: true, ecma: 2020 }, mangle: { toplevel: true } }); if (result.error) { console.error('Minification Error:', result.error); } else { console.log('Minified Code:\n', result.code); // Expected output will be a highly compressed version of the input JS // e.g., 'class Greeter{constructor(e){this.name=e}greet(){return"Hello, "+this.name+"!"}}const greeter=new Greeter("World");console.log(greeter.greet());' } } catch (e) { console.error('Unexpected Error:', e); } } runMinification();

terser --version

Debug

Known issues

breaking`uglify-es` is no longer maintained and `uglify-js` does not support ES6+ syntax. Projects using older minifiers for modern JavaScript should migrate to `terser` to avoid build failures or incorrect output.

fix

Replace `uglify-es` or `uglify-js` with `terser` in `package.json` and update build scripts accordingly.

affects: <=4.x

deprecatedThe `beautification` features in `terser` are being removed. Using beautify options may lead to unexpected behavior or future breakage. For code formatting, use a dedicated tool like Prettier.

fix

Remove any `beautify` related options from `terser` configuration. Integrate `prettier` into your development workflow for code formatting.

affects: >=5.x

gotchaWhen using the `terser` CLI, if you pass options *before* input files, you must separate them with a double dash (`--`) to prevent input files from being interpreted as option arguments.

fix

Command line usage: `terser --compress --mangle -- input.js` instead of `terser --compress --mangle input.js`.

affects: >=1.0

breakingTerser requires Node.js version 10 or higher. Running with older Node.js versions will result in errors or installation failures due to engine requirements.

fix

Upgrade your Node.js environment to version 10 or newer. Check your `package.json` `engines` field for compatibility.

affects: <=9.x (Node.js)

Errors

Common errors & fixes

SyntaxError: Unexpected token '...' (or similar for ES6+ features)

Attempting to minify modern JavaScript (ES6+) with an older minifier like `uglify-js` instead of `terser`.

fix

Ensure `terser` is installed and configured as your JavaScript minifier in your build pipeline, and that `uglify-js` is not accidentally being used.

TypeError: terser.minify is not a function

Incorrectly importing or accessing the `minify` function, often due to a wrong CommonJS `require` pattern or an invalid default import in ESM.

fix

For ESM: `import { minify } from 'terser';`. For CommonJS: `const { minify } = require('terser');`

Error: 'beautify' option is not recognized or has no effect

Using the deprecated `beautify` option in `terser` which has been removed in favor of external formatters.

fix

Remove any `beautify` options from your `terser` configuration. Use a dedicated code formatter like Prettier instead for beautification.

Upgrade

Version history

5.46.1latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

9 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/terser/terser ↗

packagehttps://www.npmjs.com/package/terser ↗

homepagehttps://terser.org ↗