Build Your Own Markdown Previewer API

The "Markdown Previewer" project involves developing a web-based application that allows users to input Markdown syntax and instantly preview the formatted content. The Markdown Previewer will support common Markdown elements such as headings, lists, links, images, code blocks, and more. Users will be able to see the raw Markdown input on one side and a live, formatted preview on the other side. The goal is to provide a seamless and interactive Markdown editing experience for users, making it easy to create and visualize Markdown content.

Detailed Description

Markdown is a lightweight markup language widely used for formatting text in web development, documentation, and technical writing. This project will create a simple, real-time Markdown Previewer that provides users with an interactive interface for editing and previewing Markdown content. Users will input raw Markdown in a text editor, and the app will render the corresponding HTML-formatted output in real time. The tool will support common Markdown elements, including:

Headings (#, ##, ###),
Bold and italic text,
Bullet points and numbered lists,
Code blocks and inline code,
Links and images,
Blockquotes and more.

Additionally, the app will allow users to toggle between light and dark themes for the editor and preview panes, making it visually adaptable to user preferences.

Example Usage

Imagine a developer writing a README file for a project. They input the Markdown content (headings, bullet points, code snippets) into the left panel of the Markdown Previewer. As they type, the preview panel on the right instantly displays a formatted version of the content, allowing them to see the result before committing the file.

Introduction
Objectives
Functional Requirements
Non-Functional Requirements
Use Cases
User Stories
Technical Requirements
API Endpoints
Security
Performance
Documentation
Glossary
Appendix

1. Introduction

The "Markdown Previewer" will provide an interactive interface for users to input Markdown syntax and instantly preview the rendered content. The application will support the core features of Markdown and allow users to toggle between light and dark themes. The project aims to create a simple, easy-to-use Markdown editing tool for developers, writers, and content creators.

2. Objectives

Enable users to input raw Markdown and view real-time HTML-formatted previews.
Support common Markdown elements like headings, lists, code blocks, and links.
Provide a dual-pane interface for side-by-side editing and previewing.
Allow users to toggle between light and dark themes for enhanced readability.
Ensure the application is responsive and works well across different devices.

3. Functional Requirements

Markdown Editing

Input Panel: Provide a text editor where users can input Markdown syntax.
Preview Panel: Display a real-time, formatted preview of the input Markdown.
Syntax Highlighting: Highlight Markdown syntax in the input panel for easier editing.

Supported Markdown Elements

Headings: Render headings using # (e.g., # Heading 1, ## Heading 2).
Bold and Italics: Support bold (**bold**) and italic (*italic*) text.
Lists: Render bullet points (- or *) and numbered lists (1.).
Links and Images: Display links ([text](url)) and images (![alt text](url)).
Code Blocks: Support inline code and code blocks (e.g., backticks).
Blockquotes: Render blockquotes using >.

Customization Options

Theme Toggle: Allow users to switch between light and dark themes.
Font Size: Provide options to adjust the font size in both the input and preview panels.

Optional Features

Save/Load Markdown Files: Allow users to save their Markdown as .md files or load existing Markdown files for editing.
Export to HTML: Provide an option to export the Markdown output as HTML.

4. Non-Functional Requirements

Scalability: Ensure the app handles large Markdown documents efficiently.
Performance: Ensure the real-time preview updates instantly with minimal latency.
Responsiveness: The app should work smoothly on desktop, tablet, and mobile devices.
Cross-Browser Compatibility: The app should function consistently across different browsers (Chrome, Firefox, Safari, Edge).

5. Use Cases

Edit Markdown: A user inputs Markdown into the editor and sees a real-time preview on the other side.
Switch Themes: A user toggles between light and dark themes to improve readability.
Save Markdown: A user saves the Markdown content to their local machine for later use.

6. User Stories

As a user, I want to input Markdown and see an instant preview so that I can check my formatting in real-time.
As a user, I want to switch between light and dark themes for better readability based on the environment I’m working in.
As a user, I want to save my Markdown content as a .md file so that I can store and use it later.
As a user, I want to be able to load a previously saved Markdown file so that I can continue editing it.

7. Technical Requirements

Frontend: Use a JavaScript framework like React or Vue.js to build the user interface.
Markdown Parser: Use a library like marked.js or markdown-it to parse Markdown into HTML.
Editor Library: Integrate a text editor library like CodeMirror or Monaco Editor for enhanced input functionality.
Real-Time Rendering: Implement real-time updates using event listeners or state management for rendering the Markdown input.

8. API Endpoints (Optional for Server Integration)

If the application needs server-side functionality, here are possible API endpoints:

Save Markdown

Endpoint: POST /api/save-markdown
Request Body:
```
json
```
Copy code
{ "content": "# My Markdown" }
Response:
```
json
```
Copy code
{ "message": "Markdown saved successfully" }

Load Markdown

Endpoint: GET /api/load-markdown/{id}
Response:
```
json
```
Copy code
{ "content": "# My Markdown" }

9. Security

HTTPS: Use HTTPS to ensure secure data transmission between the client and server.
Input Validation: Sanitize user input to prevent malicious Markdown or script injections.
File Handling: If supporting file uploads, validate and sanitize uploaded Markdown files.

10. Performance

Low Latency: Ensure that the Markdown preview updates immediately after input.
Caching: Cache recently edited Markdown content to speed up loading for returning users.

11. Documentation

Provide user documentation that explains how to use the Markdown Previewer, including supported Markdown syntax and any additional features.
Include developer documentation with setup instructions and API references (if applicable).

12. Glossary

Markdown: A lightweight markup language for formatting plain text.
HTML: Hypertext Markup Language, used for rendering web content.
Syntax Highlighting: A feature that displays Markdown syntax in different colors and fonts to improve readability.

13. Appendix

Include mockups of the Markdown Previewer interface to illustrate the user experience.

Let me know if you need any further modifications or additional details!