trex-bitmap-to-text.js

const bmpjs = require('bmp-js');
const fs = require('fs');
const happyb = fs.readFileSync('./happy-birthday.bmp');
const bitmap = bmpjs.decode(happyb);
for (x = 0; x < bitmap.width; x++) {
  let line = '';
  for (y = 0; y < bitmap.height; y++) {
    line += bitmap.data[y * bitmap.width * 4 + (bitmap.width - 1 - x) * 4 + 1] ? ' ' : '#';
  }
  console.log(line);
}