How to Use GitHub Copilot for Documentation Generation: JSDoc, README, and API Docs from Code

Why Documentation Is the Most Impactful Use of Copilot’s Capabilities

Developers hate writing documentation. The code is written, it works, and writing docs feels redundant. But documentation is the difference between a codebase that new developers can navigate in days versus one that takes weeks to understand.

Copilot makes documentation nearly effortless. Position your cursor above a function, type /**, and Copilot generates a complete JSDoc comment with parameters, return types, descriptions, and examples. Ask Copilot Chat to /doc a file and it generates comprehensive documentation. The documentation is derived from the code itself — so it is accurate by construction.

The investment: 5 seconds per function for JSDoc, 5 minutes per module for API docs. The payoff: every developer who reads the code in the future saves 10-30 minutes of reverse-engineering.

Generating JSDoc Comments

The Basic Technique

Position your cursor above any function and type /**:

/**
 * Copilot suggests:
 * Calculates the total price for an order including tax and discounts.
 * @param {OrderItem[]} items - The items in the order
 * @param {string} taxRegion - The tax region for calculating applicable tax rate
 * @param {string} [discountCode] - Optional promotional discount code
 * @returns {OrderTotal} The calculated total with subtotal, tax, discount, and final amount
 * @throws {InvalidDiscountError} If the discount code is invalid or expired
 * @example
 * const total = calculateOrderTotal(items, 'US-CA', 'SAVE20');
 * // { subtotal: 100, tax: 8.75, discount: 20, total: 88.75 }
 */
function calculateOrderTotal(items, taxRegion, discountCode) {

Using Copilot Chat for Batch Documentation

/doc Generate JSDoc for all exported functions in this file

Copilot Chat generates documentation for every public function, class, and type export in the file simultaneously.

Documentation for Complex Types

/**
 * Copilot suggests for a TypeScript interface:
 *
 * Configuration for the payment processing pipeline.
 * @property {string} gatewayId - The payment gateway identifier
 * @property {number} retryAttempts - Number of retry attempts for failed charges (default: 3)
 * @property {number} timeoutMs - Request timeout in milliseconds (default: 10000)
 * @property {boolean} idempotent - Whether to enable idempotency checks
 * @property {WebhookConfig} [webhook] - Optional webhook configuration for payment events
 */
interface PaymentConfig {

Generating README Files

Copilot Chat prompt:
"Generate a README.md for this project based on the code.
Include: project description, installation, quickstart,
API reference, configuration, and contributing guidelines.
Derive the information from package.json, the directory
structure, and the main entry point."

Copilot reads the codebase and generates a README that accurately reflects the project’s actual setup, dependencies, and usage patterns.

Generating API Documentation

Copilot Chat prompt:
"Generate API documentation for all endpoints in this file.
For each endpoint include:
- HTTP method and path
- Description
- Request body schema (with types)
- Response schema (with types and status codes)
- Example request (curl)
- Example response (JSON)

Format as Markdown."

Maintaining Documentation

The biggest documentation problem is staleness. Copilot helps by making updates easy:

After changing a function:
1. Delete the old JSDoc comment
2. Type /** above the updated function
3. Copilot generates updated documentation reflecting the changes

After adding a new endpoint:
Copilot Chat: "Update the API docs in docs/api.md to include
the new /api/projects/:id/archive endpoint I just added."

Best Practices

Document the Why, Not the What

Copilot generates “what” documentation well (parameter types, return values). Add “why” manually:

/**
 * Calculates order total with tax and discount.
 *
 * NOTE: We calculate tax BEFORE applying discounts because
 * our tax jurisdiction requires tax on the full price.
 * This was confirmed with our accountant in Q1 2026.
 * Do not change the order of operations.
 */

Review Before Committing

Copilot-generated docs are usually correct but occasionally:

Describe what the function currently does, not what it should do
Miss subtle edge cases
Use generic descriptions for complex logic

Always read generated docs before committing. The 30 seconds of review prevents misleading documentation.

Generate Documentation at Review Time

Add a pre-commit hook or PR check: “All exported functions must have JSDoc comments.” Developers can generate them instantly with Copilot, and reviewers verify they are accurate.

Frequently Asked Questions

Does Copilot generate OpenAPI/Swagger documentation?

Copilot can generate OpenAPI YAML/JSON from your route handlers. Ask: “Generate an OpenAPI 3.0 spec for all endpoints in this directory.” The output may need minor adjustments but provides a strong starting point.

Can Copilot document legacy code I did not write?

Yes. Point Copilot at any function and it generates documentation based on what the code does. This is valuable for documenting inherited codebases where no documentation exists.

Should I use Copilot or TypeDoc/JSDoc tools for documentation?

Both. Copilot writes the JSDoc comments. TypeDoc generates HTML documentation from those comments. They are complementary, not competing.

How accurate is Copilot’s documentation?

For function signatures, parameters, and return types: highly accurate (derived from the code). For descriptions of behavior and edge cases: usually accurate but should be verified. For “why” explanations: cannot generate these (add them yourself).

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