Rough script to extract images from HTTP Archive (HAR) files

har-extract.js

const fs = require('fs');
const fsAsync = require('fs').promises;
const targetMimeType = 'image/jpeg';
const file = JSON.parse(fs.readFileSync('./dump.har')).log;
const dir = './output';

if (!fs.existsSync(dir)){
  fs.mkdirSync(dir);
}

// renders a text based progress bar to the console
const width = 30;
const displayProgress = (cur, total) => {
  const pct = Math.round(cur / total * 100) / 100;
  const done = pct * width;
  const remaining = width - done;
  const filled = '\u2588'.repeat(done);
  const empty = '\u2591'.repeat(remaining);
  // '\r' clears the current line in stout
  process.stdout.write(`\r${filled}${empty} | ${Math.ceil(pct * 100)}% | ${cur} of ${total} images saved.`);
}

const promises = [];
let started = 0;
let finished = 0;
for (const entry of file.entries) {
  if (entry.response.content.mimeType === targetMimeType) {
    const pathParts = new URL(entry.request.url).pathname.split('/');
    const filename = pathParts.pop() || pathParts.pop(); // Pop twice to avoid potential trailing slash
    promises.push(fsAsync.writeFile(`${dir}/${filename}`, entry.response.content.text, 'base64')
      .then(() => {
        finished++;
        displayProgress(finished, started);
      })
      .catch(err => {
        console.log(err)
      })
    );
    started++;
  }
}

Promise.all(promises).then(() => {
  process.stdout.write(`\n\u2713 Done.`);
});