Supercharge Google Docs with Gemini AI

by

Github https://github.com/lsvekis/20-Gemini-Exercises

📘 Google Docs + Gemini AI — Complete Guide for Beginners

Supercharge Google Docs with Gemini AIDownload

Build AI-powered writing tools directly inside Google Docs using Apps Script

This guide walks you through five AI tools you can add to any Google Doc using Apps Script and Google’s Gemini API.

You’ll learn how each function works, how to use it, and how to customize it — even if you’re new to Apps Script.

⭐ Overview of the Tools

This project includes five AI-powered features inside Google Docs:

  1. Summarize selected text
  2. Rewrite selected text in simpler language
  3. Generate an outline from a topic
  4. Create multiple-choice quiz questions from selected text
  5. Suggest a constructive writing comment

All functions use a shared Gemini helper:

  • callGemini(prompt) → sends a prompt to Gemini and returns text
  • Works with your own Gemini API key stored safely in Script Properties

🧱 Project Structure

Your Apps Script project includes:

  • SharedHelpers.gs → Gemini API helper functions
  • DocsExamples.gs → All 5 Google Docs AI tools

This guide explains only the Docs functions.

🔧 Setup Instructions

1. Open a Google Doc

Go to Extensions → Apps Script.

2. Create two files:

  • SharedHelpers.gs
  • DocsExamples.gs

3. Add your API key

In the Script editor:

Project Settings → Script properties → Add script property

Key: GEMINI_API_KEY

Value: your Gemini API key

4. Paste the code

Add SharedHelpers + DocsExamples code.

5. Save, authorize, and you’re ready.

—————————————————–

🧩 EXAMPLE 1 — Summarize Selected Text

—————————————————–

✔ What it does

Select text in your Google Doc → run docs_summarizeSelection() → Gemini generates a short summary.

✔ Use cases

  • Meeting notes
  • Research papers
  • Lesson content
  • Long emails
  • Blog drafts
  • Academic reading

✔ Code

function docs_summarizeSelection() {

  const doc = DocumentApp.getActiveDocument();

  const sel = doc.getSelection();

  if (!sel) {

    DocumentApp.getUi().alert(‘Select some text first.’);

    return;

  }

  let text = ”;

  sel.getRangeElements().forEach(el => {

    const element = el.getElement();

    if (element.editAsText) {

      text += element.asText().getText() + ‘\n’;

    }

  });

  if (!text.trim()) {

    DocumentApp.getUi().alert(‘Selected text is empty.’);

    return;

  }

  const summary = callGemini(‘Summarize this text in a short paragraph:\n\n’ + text);

  DocumentApp.getUi().alert(summary);

}

✔ How it works

  • Gets the current document
  • Retrieves the user’s text selection
  • Extracts only editable text nodes
  • Passes the text to Gemini
  • Shows the summary in a popup

📝 Exercise

Select 2–3 paragraphs of text and run the function.
Try different writing styles: emails, scripts, policy documents, or lecture notes.

—————————————————–

🧩 EXAMPLE 2 — Rewrite Text in Simpler Language

—————————————————–

✔ What it does

Rewrites selected text at a Grade 6 reading level.

✔ Use cases

  • Education
  • Accessibility
  • Simplifying instructions
  • Making content easier to understand

✔ Code

function docs_rewriteSimpler() {

  const doc = DocumentApp.getActiveDocument();

  const sel = doc.getSelection();

  if (!sel) {

    DocumentApp.getUi().alert(‘Select some text first.’);

    return;

  }

  let text = ”;

  sel.getRangeElements().forEach(el => {

    const element = el.getElement();

    if (element.editAsText) {

      text += element.asText().getText() + ‘\n’;

    }

  });

  if (!text.trim()) {

    DocumentApp.getUi().alert(‘Selected text is empty.’);

    return;

  }

  const simpler = callGemini(

    ‘Rewrite the following text at a Grade 6 reading level:\n\n’ + text

  );

  DocumentApp.getUi().alert(simpler);

}

✔ How it works

Same logic as Example 1 — but Gemini receives a rewriting instruction.

📝 Exercise

Try rewriting:

  • A legal paragraph
  • A technical explanation
  • A blog paragraph
  • A definition

Compare the before/after results.

—————————————————–

🧩 EXAMPLE 3 — Generate Outline From Topic

—————————————————–

✔ What it does

Asks the user for a topic → generates a structured bullet-point outline → inserts it into the Doc.

✔ Use cases

  • Lesson planning
  • Blog post drafting
  • Speech preparation
  • Planning reports or presentations
  • Breaking down large topics

✔ Code

function docs_generateOutlineFromTopic() {

  const ui = DocumentApp.getUi();

  const response = ui.prompt(

    ‘Outline Generator’,

    ‘Enter a topic:’,

    ui.ButtonSet.OK_CANCEL

  );

  if (response.getSelectedButton() !== ui.Button.OK) return;

  const topic = response.getResponseText().trim();

  if (!topic) {

    ui.alert(‘Please enter a topic.’);

    return;

  }

  const outline = callGemini(

    ‘Create a short bullet-point outline for this topic:\n\n’ + topic

  );

  const doc = DocumentApp.getActiveDocument();

  const body = doc.getBody();

  body.appendParagraph(‘\nOutline for: ‘ + topic).setBold(true);

  body.appendParagraph(outline);

}

✔ How it works

  • Shows a prompt dialog
  • Extracts the topic
  • Calls Gemini to produce a list
  • Inserts the outline into your document

📝 Exercise

Generate outlines for:

  • “Intro to JavaScript”
  • “Climate Change”
  • “Beginner’s Guide to Investing”
  • “Marketing Plan for 2025”

—————————————————–

🧩 EXAMPLE 4 — Create Quiz Questions From Text

—————————————————–

✔ What it does

Select text → creates 5 multiple-choice questions with 4 options each, including the correct answer.

✔ Use cases

  • Teachers
  • Online courses
  • Corporate training
  • Study guides
  • Educational content creation

✔ Code

function docs_quizFromSelection() {

  const doc = DocumentApp.getActiveDocument();

  const sel = doc.getSelection();

  if (!sel) {

    DocumentApp.getUi().alert(‘Select some text first.’);

    return;

  }

  let text = ”;

  sel.getRangeElements().forEach(el => {

    const element = el.getElement();

    if (element.editAsText) {

      text += element.asText().getText() + ‘\n’;

    }

  });

  if (!text.trim()) {

    DocumentApp.getUi().alert(‘Selected text is empty.’);

    return;

  }

  const quiz = callGemini(

    ‘Based on the text below, create 5 multiple choice questions with 4 options each and mark the correct answer:\n\n’ +

      text

  );

  const body = doc.getBody();

  body.appendParagraph(‘\nGenerated Quiz:’).setBold(true);

  body.appendParagraph(quiz);

}

✔ How it works

  • Extracts selected text
  • Passes it to Gemini with quiz-generation instructions
  • Inserts the quiz into the Doc

📝 Exercise

Select a Wikipedia paragraph and generate a quiz.
Try with chapters from textbooks, training documents, or blog posts.

—————————————————–

🧩 EXAMPLE 5 — Suggest a Constructive Comment

—————————————————–

✔ What it does

Reads selected text → suggests an editor-style writing improvement.

✔ Use cases

  • Editing drafts
  • Peer review
  • Improving clarity
  • Coaching writers
  • Giving feedback

✔ Code

function docs_suggestComment() {

  const doc = DocumentApp.getActiveDocument();

  const sel = doc.getSelection();

  if (!sel) {

    DocumentApp.getUi().alert(‘Select some text first.’);

    return;

  }

  let text = ”;

  sel.getRangeElements().forEach(el => {

    const element = el.getElement();

    if (element.editAsText) {

      text += element.asText().getText() + ‘\n’;

    }

  });

  if (!text.trim()) {

    DocumentApp.getUi().alert(‘Selected text is empty.’);

    return;

  }

  const comment = callGemini(

    ‘You are a helpful writing coach. Suggest one constructive comment to improve this text:\n\n’ +

      text

  );

  DocumentApp.getUi().alert(‘Suggested comment:\n\n’ + comment);

}

✔ How it works

Prompts Gemini to behave like a writing coach and evaluate the selected text.

📝 Exercise

Try selecting:

  • A paragraph of your own writing
  • A blog intro
  • A product description
  • A social media post

🧠 How All Functions Work Behind the Scenes

Step 1 — Detect the user’s selection

Google Docs scripts can detect selected elements, but not styles or layout.

Step 2 — Combine the text into a single string

Line separation helps Gemini process the content.

Step 3 — Generate the prompt

Each function uses a clear natural-language instruction.

Step 4 — Send the prompt to Gemini

callGemini(prompt) does all the heavy lifting.

Step 5 — Display or insert the result

Alerts are used for display, and the document body for insertions.

🧪 How to Run These Functions

Method 1 — Direct from editor

In Apps Script:

  • Select a function (e.g., docs_summarizeSelection)
  • Click ▶ Run

Method 2 — Add a custom menu (optional)

I can generate this if you want:

✔ “AI Tools” menu
✔ Buttons for each feature
✔ No coding knowledge required for users

🎓 Final Thoughts

These five examples give you a full foundation for building advanced Gemini tools inside Google Docs. From rewriting to summarizing, generating outlines, creating quizzes, or giving feedback — this toolkit turns Docs into a smart AI writing assistant.

/**
 * Gemini + Google Docs Examples
 *
 * REQUIREMENT:
 *  - This project must be bound to a Google Doc (open a Doc → Extensions → Apps Script).
 *  - SharedHelpers.gs must be in the same project (for callGemini()).
 */

/**
 * EXAMPLE 1 — Summarize selected text
 */
function docs_summarizeSelection() {
  const doc = DocumentApp.getActiveDocument();
  const sel = doc.getSelection();

  if (!sel) {
    DocumentApp.getUi().alert('Select some text first.');
    return;
  }

  let text = '';
  sel.getRangeElements().forEach(el => {
    const element = el.getElement();
    if (element.editAsText) {
      text += element.asText().getText() + '\n';
    }
  });

  if (!text.trim()) {
    DocumentApp.getUi().alert('Selected text is empty.');
    return;
  }

  const summary = callGemini('Summarize this text in a short paragraph:\n\n' + text);
  DocumentApp.getUi().alert(summary);
}

/**
 * EXAMPLE 2 — Rewrite selected text in simpler language
 */
function docs_rewriteSimpler() {
  const doc = DocumentApp.getActiveDocument();
  const sel = doc.getSelection();

  if (!sel) {
    DocumentApp.getUi().alert('Select some text first.');
    return;
  }

  let text = '';
  sel.getRangeElements().forEach(el => {
    const element = el.getElement();
    if (element.editAsText) {
      text += element.asText().getText() + '\n';
    }
  });

  if (!text.trim()) {
    DocumentApp.getUi().alert('Selected text is empty.');
    return;
  }

  const simpler = callGemini(
    'Rewrite the following text at a Grade 6 reading level:\n\n' + text
  );
  DocumentApp.getUi().alert(simpler);
}

/**
 * EXAMPLE 3 — Generate outline from a topic (prompt dialog)
 */
function docs_generateOutlineFromTopic() {
  const ui = DocumentApp.getUi();
  const response = ui.prompt(
    'Outline Generator',
    'Enter a topic:',
    ui.ButtonSet.OK_CANCEL
  );

  if (response.getSelectedButton() !== ui.Button.OK) return;

  const topic = response.getResponseText().trim();
  if (!topic) {
    ui.alert('Please enter a topic.');
    return;
  }

  const outline = callGemini(
    'Create a short bullet-point outline for this topic:\n\n' + topic
  );

  const doc = DocumentApp.getActiveDocument();
  const body = doc.getBody();
  body.appendParagraph('\nOutline for: ' + topic).setBold(true);
  body.appendParagraph(outline);
}

/**
 * EXAMPLE 4 — Create quiz questions from selected text
 */
function docs_quizFromSelection() {
  const doc = DocumentApp.getActiveDocument();
  const sel = doc.getSelection();

  if (!sel) {
    DocumentApp.getUi().alert('Select some text first.');
    return;
  }

  let text = '';
  sel.getRangeElements().forEach(el => {
    const element = el.getElement();
    if (element.editAsText) {
      text += element.asText().getText() + '\n';
    }
  });

  if (!text.trim()) {
    DocumentApp.getUi().alert('Selected text is empty.');
    return;
  }

  const quiz = callGemini(
    'Based on the text below, create 5 multiple choice questions with 4 options each and mark the correct answer:\n\n' +
      text
  );

  const body = doc.getBody();
  body.appendParagraph('\nGenerated Quiz:').setBold(true);
  body.appendParagraph(quiz);
}

/**
 * EXAMPLE 5 — Suggest a constructive comment for selected text
 */
function docs_suggestComment() {
  const doc = DocumentApp.getActiveDocument();
  const sel = doc.getSelection();

  if (!sel) {
    DocumentApp.getUi().alert('Select some text first.');
    return;
  }

  let text = '';
  sel.getRangeElements().forEach(el => {
    const element = el.getElement();
    if (element.editAsText) {
      text += element.asText().getText() + '\n';
    }
  });

  if (!text.trim()) {
    DocumentApp.getUi().alert('Selected text is empty.');
    return;
  }

  const comment = callGemini(
    'You are a helpful writing coach. Suggest one constructive comment to improve this text:\n\n' +
      text
  );

  DocumentApp.getUi().alert('Suggested comment:\n\n' + comment);
}