Anser - ANSI Sequence Parser

2.3.5 verified Sat Apr 25 auth: no javascript

Anser is a low-level parser for ANSI escape codes, converting terminal text with color/style sequences into HTML elements, JSON, or plain text. Version 2.3.5 is the current stable release, with infrequent updates focused on bug fixes and edge cases. Key differentiators: supports true color (24-bit), 256-color palette, and SGR parameters; provides both HTML and JSON output; includes link detection and HTML escaping; has TypeScript definitions. Alternatives like chalk focus on terminal output, not parsing, while ansi-to-html is less feature-rich. Released under MIT license.

Common errors

error Cannot find module 'anser' or its corresponding type declarations. ↓

cause Missing @types/anser or package not installed.

fix

npm install anser (types included) or yarn add anser. No separate @types needed.

error TypeError: Anser.ansiToHtml is not a function ↓

cause Using default import without default export syntax in CommonJS environment.

fix

Use import Anser from 'anser' (ESM) or const Anser = require('anser').default (CommonJS).

error Module '"anser"' has no exported member 'ansiToHtml'. ↓

cause Trying named import from anser when it's not exported that way in TypeScript without esModuleInterop.

fix

Use import Anser from 'anser' and call Anser.ansiToHtml, or enable esModuleInterop.

error Cannot use import statement outside a module ↓

cause Using ESM import syntax in a CommonJS script without 'type':'module' in package.json.

fix

Add "type": "module" to package.json or rename file to .mjs.

Warnings

breaking ESM-only package since v2 with no CommonJS main export; require('anser') may not work in Node.js without package.json exports field support. ↓

fix Use import syntax or set type: 'module' in package.json. For CommonJS, use dynamic import or await import('anser').

deprecated The ansiToJson method's output includes a 'isEmpty' function property which may be removed in future versions. ↓

fix Access json object properties directly without relying on isEmpty function. Use content, fg, bg, etc.

gotcha TypeScript definition export changed in v2.0.2; importing as namespace may fail without esModuleInterop. ↓

fix Enable esModuleInterop in tsconfig.json, or use import Anser = require('anser') and use as namespace.

gotcha ansiToHtml with use_classes uses palette-based class names (e.g., 'ansi-palette-196-fg') which may not match CSS frameworks expecting different naming. ↓

fix Customize class names by mapping the palette yourself, or use inline styles (default).

deprecated The 'linkify' option in ansiToHtml was removed in v2.0.0; use external linkification. ↓

fix Pre-process text with a linkify library before passing to anser.

gotcha Grayscale palette colors (in 256-color mode) may return undefined for some indices. ↓

fix Update to v2.3.5+ which fixes grayscale palette returning undefined.

Install

npm install anser

yarn add anser

pnpm add anser

Imports

Anser
wrong
```
const Anser = require('anser')
```
correct
```
import Anser from 'anser'
```
ESM default import. For CommonJS use require('anser').default or use the import syntax shown. TypeScript with --esModuleInterop uses default import; without, use import Anser = require('anser').
ansiToHtml
wrong
```
import { Anser } from 'anser'
```
correct
```
import { ansiToHtml } from 'anser'
```
Named export for the function. Alternatively use Anser.ansiToHtml as a static method.

escapeForHtml

wrong

const escapeForHtml = require('anser').escapeForHtml

correct

import { escapeForHtml } from 'anser'

Helper function to escape HTML entities. Available as named export.

Quickstart

Demonstrates converting ANSI-colored text to HTML with inline styles, CSS classes, JSON, and plain text removal.

import Anser from 'anser';

const txt = "\u001b[38;5;196mHello\u001b[39m \u001b[48;5;226mWorld\u001b[49m";

// Convert to HTML with inline styles
const html = Anser.ansiToHtml(txt);
console.log(html);
// <span style="color:rgb(255, 0, 0)">Hello</span> <span style="background-color:rgb(255, 255, 0)">World</span>

// Convert to HTML with CSS classes
const htmlClasses = Anser.ansiToHtml(txt, { use_classes: true });
console.log(htmlClasses);
// <span class="ansi-palette-196-fg">Hello</span> <span class="ansi-palette-226-bg">World</span>

// Convert to JSON
const json = Anser.ansiToJson(txt);
console.log(JSON.stringify(json[1]));
// {"content":"Hello","fg":"255, 0, 0","bg":null,"fg_truecolor":null,"bg_truecolor":null,"clearLine":false,"decoration":null,"was_processed":true}

// Remove ANSI codes (plain text)
const plain = Anser.ansiToText(txt);
console.log(plain);
// Hello World