Deno Progress Bar

progress.ts

import { tty } from "https://deno.land/x/[email protected]/ansi/tty.ts";

interface ProgressBarOptions {
  label?: string;
  total?: number;
  width?: number;
}

/**
 * A simple progress bar for Deno
 * @param options
 *  - `label` - The label to display before the progress bar
 *  - `total` - The total number of steps to completion
 *  - `width` - The width of the progress bar (defaults to the width of the terminal)
 * @constructor
 * @example
 * const bar = new ProgresBar({ label: "Downloading", total: 100 });
 * for (let i = 0; i <= 100; i++) {
 *   bar.update(i);
 *    await sleep(100);
 * }
 */
export class ProgressBar {
  private label = "";
  private total: number;
  private barWidth: number;
  private barStart: number;
  private barEnd: number;
  private pctStart = 0;
  private pctLength = "100.0%".length;

  private chars = ["░", "▒", "▓", "█"];

  private _tty = tty({
    stdout: Deno.stdout,
    stdin: Deno.stdin,
  });

  constructor(options?: ProgressBarOptions) {
    const columns = Deno.consoleSize().columns;
    this.label = options?.label ?? "Progress";
    this.total = options?.total ?? 100;
    this.pctStart = columns - this.pctLength;
    this.barEnd = this.pctStart - 1;
    this.barStart = this.label.length + 1;
    this.barWidth = options?.width ?? this.barEnd - this.barStart;
  }

  update(i: number) {
    const pct = i / this.total;
    const pctText = `${(i / this.total * 100).toFixed(1)}%`.padStart(
      this.pctLength,
    );

    const filled = this.barWidth * pct;
    const filledWhole = Math.floor(filled);

    const bar = this.chars[this.chars.length - 1].repeat(filledWhole);
    const empty = this.chars[0].repeat(
      Math.max(0, this.barWidth - filledWhole - 1),
    );
    const str = `${this.label} ${bar}${empty} ${pctText}`;

    this._tty.text(str).cursorLeft();
  }
}

progress_test.ts

const sleep = (ms: number) => {
  return new Promise((resolve) => setTimeout(resolve, ms));
};

const loop = async () => {
  const pb = new ProgresBar();

  for (let i = 0; i < 100; i++) {
    await sleep(20);
    pb.update(i);
  }
};

await loop();