Inline progress bar

prettyPrintProgress.ts

import * as readline from 'readline'
import { performance } from 'perf_hooks';


const delay = <T>(ms: number, returnValue: T = undefined): Promise<T> =>
  new Promise(resolve => setTimeout(() => resolve(returnValue), ms));

const showPercentage = (percentage: string) => {
  readline.cursorTo(process.stdout, 0, null);
  let text = `working ... ${percentage}%`
  process.stdout.write(text);
}

const abc = async (items: number[]) => {
  const total = items.length;
  for (let i = 1; i <= total; i++) {
    await delay(15)
    showPercentage(((i / total) * 100).toFixed(2));
  }
  process.stdout.write("\n");
}

const main = async () => {
  try {
    const items = Array.from(Array(5000), (_, i) => i)
    const start = performance.now();
    await abc(items);
    const elapsed = performance.now() - start;
    console.log(`Total time for ${items.length} items: ${elapsed}ms.`);
    console.log(`Avg Time for each item: ${elapsed / items.length}ms.`);
    return 'done';
  } catch (e) {
    return `not done. Error: ${e.message}`;
  }
}

main();