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Creating Your Own Markdown Editor with JavaScript

If you want to build a Markdown editor, JavaScript is a great tool. Let’s dive into steps you can follow to make it happen.

TL;DR: Quick Summary

To create a Markdown editor with JavaScript, use the following code snippet:


// HTML Structure










').replace(/[*]{2}(.*?)[*]{2}/g, '$1');
}


This snippet sets up a basic markdown editor using HTML and JavaScript. Keep reading for a more detailed guide.

Setting Up the HTML Structure

The first step to creating a Markdown editor is setting up your HTML structure.

You need a textarea for users to input their markdown code.

A div is necessary to display the rendered HTML.

Here is a simple HTML structure for a Markdown editor:












Writing the JavaScript Code

Now, you need to write the JavaScript to handle input and convert it to HTML.

Start by getting references to your textarea and div:


const textarea = document.getElementById('markdown');
const preview = document.getElementById('preview');


Add an event listener to handle input changes in the textarea:


textarea.addEventListener('input', () => {
const markdownText = textarea.value;
const htmlText = convertMarkdownToHtml(markdownText);
preview.innerHTML = htmlText;
});


Next, write a function to convert Markdown to HTML.

This function will be simple and only translate basic Markdown.

For more robust features, consider using a library like marked.js.


function convertMarkdownToHtml(markdown) {
// Replace Markdown syntax with HTML tags
return markdown.replace(/#/g, '

')
.replace(/[*]{2}(.*?)[*]{2}/g, '$1');
}


Enhancing Markdown Rendering with Libraries

While our basic converter works, libraries can simplify the process.

One popular choice is marked.js.

First, include marked.js in your project.

You can use a CDN:

Or install it via npm if you are using a build tool:


npm install marked


Updated JavaScript code to use marked.js for conversion:


textarea.addEventListener('input', () => {
const markdownText = textarea.value;
const htmlText = marked(markdownText);
preview.innerHTML = htmlText;
});


Styling the Editor with CSS

Don’t forget to style your Markdown editor.

Simple CSS to improve the look:

Managing State with LocalStorage

Preserve user input between sessions with LocalStorage.

Load saved markdown from LocalStorage when the page loads:


document.addEventListener('DOMContentLoaded', () => {
const savedMarkdown = localStorage.getItem('markdown');
if (savedMarkdown) {
textarea.value = savedMarkdown;
preview.innerHTML = marked(savedMarkdown);
}
});


Save markdown to LocalStorage whenever it changes:


textarea.addEventListener('input', () => {
const markdownText = textarea.value;
localStorage.setItem('markdown', markdownText);
const htmlText = marked(markdownText);
preview.innerHTML = htmlText;
});


Adding Useful Features

Consider adding more features to enhance the user experience.

These can include:

• Syntax highlighting with a library such as highlight.js.
• Auto-saving content.
• Toolbar for Markdown formatting shortcuts.

Using highlight.js for syntax highlighting:

Include the library via CDN:

Initialize highlight.js after rendering HTML:


textarea.addEventListener('input', () => {
const markdownText = textarea.value;
const htmlText = marked(markdownText);
preview.innerHTML = htmlText;
document.querySelectorAll('pre code').forEach((block) => {
hljs.highlightBlock(block);
});
});


Frequently Asked Questions

How can I add toolbar buttons for formatting?

Create buttons in HTML and add event listeners to insert Markdown syntax.

What if I need to support more complex Markdown features?

Use a JavaScript library like marked.js or markdown-it for full functionality.

Why isn’t my Markdown converting properly?

Check if your conversion logic supports the specific Markdown syntax.

It’s also possible a library like marked.js may need configuration.

How can I save and load user input?

Use localStorage to save input and load it when the page loads.

Can I export the Markdown as a file?

Yes, use JavaScript to create a downloadable .md or .html file.

Is there a way to preview live HTML?

The render method in the code provides instant preview as you type.

What about mobile usability?

Ensure your CSS is responsive to provide a good experience on all devices.

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Using Markdown-It for More Features

If you need to support more complex Markdown features, consider using markdown-it.

First, include markdown-it in your project:

You can use a CDN:

Or install it via npm if you are using a build tool:


npm install markdown-it


Updated JavaScript code to use markdown-it for conversion:


const md = new markdownit();
textarea.addEventListener('input', () => {
const markdownText = textarea.value;
const htmlText = md.render(markdownText);
preview.innerHTML = htmlText;
});


Using Highlight.js with Markdown-It

Integrate syntax highlighting with markdown-it and highlight.js.

Include highlight.js along with markdown-it:

Initialize highlight.js with markdown-it:


const md = new markdownit({
highlight: function (str, lang) {
if (lang && hljs.getLanguage(lang)) {
try {
return '

' +
                       hljs.highlight(lang, str, true).value +
                       '

' + md.utils.escapeHtml(str) + '

';
}
});
textarea.addEventListener('input', () => {
const markdownText = textarea.value;
const htmlText = md.render(markdownText);
preview.innerHTML = htmlText;
});


Adding Toolbar Buttons for Formatting

Enhance the user experience by adding toolbar buttons for common Markdown formatting.

Start by creating buttons in HTML:

Add event listeners to insert Markdown syntax:


document.getElementById('boldBtn').addEventListener('click', () => {
insertAtCursor('**bold**');
});

function insertAtCursor(text) {
const startPos = textarea.selectionStart;
const endPos = textarea.selectionEnd;
textarea.value = textarea.value.substring(0, startPos) + text + textarea.value.substring(endPos, textarea.value.length);
textarea.focus();
textarea.selectionStart = startPos + text.length;
textarea.selectionEnd = startPos + text.length;
}


Implementing Auto-Save Functionality

Automatically save the user’s progress to avoid data loss.

Already discussed saving to LocalStorage but you can implement auto-save on an interval:


setInterval(() => {
const markdownText = textarea.value;
localStorage.setItem('markdown', markdownText);
const htmlText = md.render(markdownText);
preview.innerHTML = htmlText;
}, 5000); // Auto-save every 5 seconds


Exporting Markdown as a File

Allow users to export their Markdown as a file.

Provide a button for exporting:


Export


Add an event listener for exporting the Markdown:


document.getElementById('exportBtn').addEventListener('click', () => {
const markdownText = textarea.value;
const blob = new Blob([markdownText], { type: 'text/markdown' });
const url = URL.createObjectURL(blob);
const a = document.createElement('a');
a.href = url;
a.download = 'markdown.md';
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
});


Frequently Asked Questions

How can I add toolbar buttons for formatting?

Create buttons in HTML and add event listeners to insert Markdown syntax.

What if I need to support more complex Markdown features?

Use a JavaScript library like marked.js or markdown-it for full functionality.

Why isn’t my Markdown converting properly?

Check if your conversion logic supports the specific Markdown syntax.

It’s also possible a library like marked.js may need configuration.

How can I save and load user input?

Use localStorage to save input and load it when the page loads.

Can I export the Markdown as a file?

Yes, use JavaScript to create a downloadable .md or .html file.

Is there a way to preview live HTML?

The render method in the code provides instant preview as you type.

What about mobile usability?

Ensure your CSS is responsive to provide a good experience on all devices.

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