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Free JavaScript Library for Fonts Parsing & Writing

Open Source JavaScript Library that allows to Parse, Read and write TrueType or OpenType fonts. It support Font Handling, Glyph Metrics & Text Layout inside JS apps.

In the vast kingdom of web design and development, typography plays a pivotal role in shaping the overall user experience However, working with typography on the web has its own set of challenges. Thankfully, opentype.js, an open-source JavaScript library, has emerged as a powerful tool that empowers software developers to manipulate and harness the potential of typography in web applications. The library provides a simple and intuitive API, making it accessible to developers of all skill levels. It empowers developers with the flexibility to customize and adapt typography to suit their specific design requirements.

Opentype.js works across a wide range of modern web browsers, making it a reliable and consistent solution for implementing typographic features. There are several important features part of the library, such as robust font parsing mechanism, interact with individual glyphs within a font, complex text layout support, various fonts rendering, cross-browser compatibility, extract detailed font data, advanced text layout support, animate individual glyphs and many more. It is seamlessly integrates with existing web technologies and can be used with HTML5 canvas, SVG, or even combined with CSS and JavaScript frameworks.

Opentype.js is an open source JavaScript library that allows web developers to work with OpenType fonts, a widely used font format. OpenType fonts offer advanced typographic features, such as ligatures, kerning, and glyph substitutions, which greatly enhance the visual appeal and readability of text. By leveraging opentype.js, software developers can unlock these features and access the underlying data of OpenType fonts, enabling them to create dynamic and interactive typographic experiences on the web. Whether it's fine-tuning typographic details or creating intricate typographic animations, OpenType.js is an invaluable tool for anyone passionate about the art of typography in the digital realm.

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Getting Started with Opentype.js

The recommended way to install Opentype.js is using npm. Please use the following command to add the maven dependency in your project.

Install Opentype.js via npm

 npm install opentype.js

You can also install it manually; download the latest release files directly from GitHub repository.

Accessing Font Data via JavaScript API

One of the key features of OpenType.js is its ability to extract detailed font data with just a couple of lines of JavaScript code. The open source Opentype.js library has provided complete functionality for loading and accessing Fonts related data inside their JavaScript applications. Developers can access various attributes such as font name, designer information, glyph shapes, kerning pairs, and much more. This information enables precise control over typography and facilitates creative experimentation. The following example shows how to load and display fonts related data using JavaScript commands.

How to Display Fonts Related Data inside JavaScript Apps?

function displayFontData() {
    document.getElementById("font-data").innerHTML = JSON.stringify(font.tables, null, 4);
	var html, tablename, table, property, value;
	for(tablename in font.tables) {
		table = font.tables[tablename];
		html = '';
		for(property in table) {
			value = table[property];
			html += '
'; html += value; html += '
'; } document.getElementById(tablename+"-table").innerHTML = html; } } function onFontLoaded(font) { @@ -331,6 +384,13 @@

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fontSizeSlider.addEventListener('input', fontSizeChanged, false); fontSizeSlider.addEventListener('change', fontSizeChanged, false); var tableHeaders = document.getElementById('font-data').getElementsByTagName('h3'); for(var i = tableHeaders.length; i--; ) { tableHeaders[i].addEventListener('click', function(e) { e.target.className = (e.target.className === 'collapsed') ? 'expanded' : 'collapsed'; }, false); } opentype.load(fontFileName, function (err, font) { var amount, glyph, ctx, x, y, fontSize; if (err) { showErrorMessage(err.toString()); return; } onFontLoaded(font); });

Open & Parse Fonts inside JavaScript Apps

The open source Opentype.js library enables software developers to load and convert various types of fonts inside own JavaScript applications. The library provides a robust font parsing mechanism, allowing developers to load OpenType (WOFF, OTF, TTF) font files into their web applications. Once the font is loaded, developers can access and manipulate various font properties, such as glyph shapes, metrics, and metadata. The following example shows how to Load various types of fonts like WOFF, OTF, TTF fonts inside JavaScript apps.

How to Load a WOFF or TTF Fonts via JavaScript API?

// case 1: from an URL
const buffer = fetch('/fonts/my.woff').then(res => res.arrayBuffer());
// case 2: from filesystem (node)
const buffer = require('fs').promises.readFile('./my.woff');
// case 3: from an 
const buffer = document.getElementById('myfile').files[0].arrayBuffer();

// if running in async context:
const font = opentype.parse(await buffer);

// if not running in async context:
buffer.then(data => {
    const font = opentype.parse(data);