Introduction to ansi-regex

ansi-regex is a powerful library for matching ANSI escape codes using regular expressions. It’s typically used to strip or identify ANSI escape sequences in strings. This guide will provide an introduction to ansi-regex, explain its API, and offer practical examples on how to use it efficiently.

Installation

  
  npm install ansi-regex
  

Basic Usage

Create a simple ansi-regex instance to match standard ANSI escape codes:

  
  const ansiRegex = require('ansi-regex');
  const regex = ansiRegex();
  console.log(regex.test('\u001B[4mUnicorn\u001B[0m')); // true
  

Identifying ANSI Escape Codes

Get all ANSI escape codes in a string:

  
  const ansiRegex = require('ansi-regex');
  const string = '\u001B[4mUnicorn\u001B[0m \u001B[31mRainbow\u001B[39m';
  console.log(string.match(ansiRegex())); // ['\u001B[4m', '\u001B[0m', '\u001B[31m', '\u001B[39m']
  

Stripping ANSI Escape Codes

Remove all ANSI escape codes from a string:

  
  const ansiRegex = require('ansi-regex');
  const string = '\u001B[4mUnicorn\u001B[0m \u001B[31mRainbow\u001B[39m';
  const strippedString = string.replace(ansiRegex(), '');
  console.log(strippedString); // Unicorn Rainbow
  

Advanced Use-Cases and Examples

Building a CLI Tool

  
  #!/usr/bin/env node
  const ansiRegex = require('ansi-regex');
  const fs = require('fs');
  const filePath = process.argv[2];

  if (!filePath) {
    console.error('Please provide a file path');
    process.exit(1);
  }

  fs.readFile(filePath, 'utf8', (err, data) => {
    if (err) {
      console.error('Error reading file:', err);
      process.exit(1);
    }
    const strippedData = data.replace(ansiRegex(), '');
    console.log(strippedData);
  });
  

Using ansi-regex with a Web App

This example demonstrates how to strip ANSI escape codes from user input before displaying it in a web app:

  
  const express = require('express');
  const ansiRegex = require('ansi-regex');
  const app = express();
  app.use(express.json());

  app.post('/sanitize', (req, res) => {
    const input = req.body.input;
    const sanitizedInput = input.replace(ansiRegex(), '');
    res.send({ sanitizedInput });
  });

  app.listen(3000, () => {
    console.log('Server is running on port 3000');
  });
  

Conclusion

ansi-regex is an essential tool for anyone dealing with ANSI escape codes in Node.js environments. It provides a simple yet powerful API to identify and strip ANSI codes, making your development process smoother and your applications more robust.

Enhance your terminal string handling capabilities with ansi-regex, and explore the myriad ways it can be utilized in your projects.

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