Live progress log line for node CLI apps

node-log-progress.js

function lpad(numOrStr, size) {
  let s = `${numOrStr}`;
  while (s.length < size) {
    s = ` ${s}`;
  }
  return s;
}
/**
 * Live progress log on a single shell line.
 * Outputs a live line in the console like:
 * `  24 / 2345   (1%)`
 *
 * Usage:
 * ```js
 * console.log("starting");
 * for (let i = 0; i < 1000; i += Math.random() * 10) {
 *   logProgress(i, 1000);
 * }
 * console.log(""); // to start a new line in the shell
 * ```
 */
export function logProgress(count, total) {
  const padSize = total.toString().length;
  const percent = Math.round(100 * count / total);
  // Create a padded count string like `   1` or `1234`
  const countText = lpad(count, padSize)
  // Create a padded percent string like: `  (2%)`, ` (12%)` or `(100%)`
  const percentText = lpad(`(${percent}%)`, 6);
  process.stdout.clearLine(-1);
  process.stdout.cursorTo(0);
  process.stdout.write(`${countText} / ${total} ${percentText}`);
}