RunLength Encoding (RLE) text compression using Unicode symbols

run-length-compression.js

/**
 * Run-Length Encoding (RLE) text compression using Unicode symbols.
 * 
 * This algorithm compresses text by counting the number of consecutive identical
 * characters in the input string and representing them in a compact format within
 * the compressed string using Unicode characters. The encoded and decoded parts
 * are separated by a Unicode private-use character, U+FFF0.
 *
 * @param {string} inputText - The text to be compressed.
 * @returns {string} - The compressed text.
 */
function compress(inputText) {
  let compressedText = '';
  let count = 1;

  for (let i = 1; i <= inputText.length; i++) {
    if (inputText[i] === inputText[i - 1]) {
      count++;
    } else {
      compressedText += String.fromCharCode(count + 0xFFF0) + inputText[i - 1];
      count = 1;
    }
  }

  return compressedText;
}

/**
 * Decompresses text that has been compressed using the RLE compression function.
 * 
 * @param {string} compressedText - The compressed text to be decompressed.
 * @returns {string} - The decompressed, original text.
 */
function decompress(compressedText) {
  let decompressedText = '';

  for (let i = 0; i < compressedText.length; i += 2) {
    let count = compressedText.charCodeAt(i) - 0xFFF0;
    let character = compressedText[i + 1];
    decompressedText += character.repeat(count);
  }

  return decompressedText;
}

// Usage example:
const originalText = "WWLLLWLWWWWLWWWLLWLLLWWWLLWWWLWLLLLLWLLLWLWWLLLWWW";
// Original Text: WWLLLWLWWWWLWWWLLWLLLWWWLLWWWLWLLLLLWLLLWLWWLLLWWW

const compressed = compress(originalText);
console.log("Compressed:", compressed); 
// Compressed: ￲W￳L￱W￱L￴W￱L￳W￲L￱W￳L￳W￲L￳W￱L￱W￵L￱W￳L￱W￱L￲W￳L￳W

const decompressed = decompress(compressed);
console.log("Decompressed:", decompressed);
// Decompressed: WWLLLWLWWWWLWWWLLWLLLWWWLLWWWLWLLLLLWLLLWLWWLLLWWW