default zoom for google docs userscript

docs-zoom.js

// ==UserScript==
// @name         Default Zoom for Google Docs/Sheets
// @namespace    default-zoom-google-workspace
// @version      1.0
// @description  Automatically sets your preferred zoom level in Google Docs and Sheets on load, by simulating the zoom menu clicks (since Google exposes no API for this).
// @match        https://docs.google.com/document/d/*
// @match        https://docs.google.com/spreadsheets/d/*
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_registerMenuCommand
// @run-at       document-idle
// ==/UserScript==

(function () {
  'use strict';

  const STORAGE_KEY = 'defaultZoomPercent';
  const VALID_ZOOMS = [50, 75, 90, 100, 125, 150, 175, 200];
  const DEFAULT_ZOOM = GM_getValue(STORAGE_KEY, 100);
  const MAX_WAIT_MS = 15000;
  const POLL_INTERVAL = 200;

  // Let user pick/change their preferred zoom via Tampermonkey menu
  GM_registerMenuCommand('Set default zoom level…', () => {
    const input = prompt(
      `Enter default zoom (${VALID_ZOOMS.join(', ')}):`,
      String(DEFAULT_ZOOM)
    );
    const value = parseInt(input, 10);
    if (VALID_ZOOMS.includes(value)) {
      GM_setValue(STORAGE_KEY, value);
      alert(`Default zoom set to ${value}%. Reload the doc to apply.`);
    } else if (input !== null) {
      alert('Invalid value. Choose one of: ' + VALID_ZOOMS.join(', '));
    }
  });

  // Skip work if already at the desired zoom
  function getCurrentZoomButton() {
    // Docs/Sheets render the current zoom % as a clickable toolbar control.
    // Match by visible text like "100%" rather than brittle dynamic IDs.
    const candidates = document.querySelectorAll(
      '[role="button"], .goog-inline-block, .docs-icon-button-content'
    );
    for (const el of candidates) {
      const text = (el.textContent || '').trim();
      if (/^\d{2,3}%$/.test(text)) {
        return el;
      }
    }
    return null;
  }

  function findMenuItemByPercent(percent) {
    const items = document.querySelectorAll(
      '[role="menuitem"], [role="menuitemradio"], .goog-menuitem'
    );
    for (const item of items) {
      const text = (item.textContent || '').trim();
      if (text === `${percent}%`) {
        return item;
      }
    }
    return null;
  }

  function clickElement(el) {
    if (!el) return false;
    el.dispatchEvent(new MouseEvent('mousedown', { bubbles: true, cancelable: true }));
    el.dispatchEvent(new MouseEvent('mouseup', { bubbles: true, cancelable: true }));
    el.dispatchEvent(new MouseEvent('click', { bubbles: true, cancelable: true }));
    return true;
  }

  function setZoom(percent) {
    const zoomButton = getCurrentZoomButton();
    if (!zoomButton) return false;

    // Already at target zoom — skip
    if (zoomButton.textContent.trim() === `${percent}%`) {
      return true;
    }

    // Open the zoom dropdown
    clickElement(zoomButton);

    // Wait a tick for the menu to render, then click the matching option
    setTimeout(() => {
      const menuItem = findMenuItemByPercent(percent);
      if (menuItem) {
        clickElement(menuItem);
      } else {
        // Close menu if we couldn't find a match, to avoid leaving it open
        document.body.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }));
      }
    }, 150);

    return true;
  }

  function waitForToolbarAndApply() {
    const start = Date.now();
    const interval = setInterval(() => {
      const zoomButton = getCurrentZoomButton();
      if (zoomButton) {
        clearInterval(interval);
        setZoom(DEFAULT_ZOOM);
      } else if (Date.now() - start > MAX_WAIT_MS) {
        clearInterval(interval);
        console.warn('[Default Zoom] Toolbar zoom control not found, giving up.');
      }
    }, POLL_INTERVAL);
  }

  waitForToolbarAndApply();
})();