Take 10 minutes to get started with Handlebars

In the fast-paced world of front-end development, it‘s easy to get caught up in the latest and greatest JavaScript frameworks. But sometimes, what you really need is a simple, effective tool that just gets the job done. Enter Handlebars.js.

Handlebars has been a quiet workhorse of the front-end ecosystem for over a decade, powering the dynamic views of countless websites and applications. In this in-depth tutorial, we‘ll explore what makes Handlebars so special and learn how to start using it in your projects in just 10 minutes.

What is Handlebars.js?

Handlebars is a simple templating language that lets you generate HTML markup with plain JavaScript. It‘s largely compatible with Mustache templates but includes more powerful features.

Handlebars was created by Yehuda Katz in 2010 as a superset of Mustache, with the goal of providing a more expressive and feature-rich templating solution. Since then, it has been continuously improved and has seen widespread adoption.

Some key advantages of Handlebars:

• Logic-less templates keep the view and code nicely separated
• Minimal runtime size at only 4.3KB gzipped
• Integrates seamlessly with any existing web stack
• Supports block expressions, helpers, and partials for code reuse
• Precompilation allows templates to be rendered on the server or client

Best of all, the syntax is simple and approachable for developers of all skill levels. Here‘s a basic example:

<div class="entry">

  <div class="body">
    {{body}}  
  </div>
</div>

The double curly braces {{ and }} denote a Handlebars expression, which will look up the corresponding property in the current context and insert its value into the template.

How Handlebars works under the hood

To truly appreciate the power and performance of Handlebars, it‘s helpful to understand a bit about how it works internally.

When you compile a Handlebars template, it gets turned into a JavaScript function. This function takes a context object as input and returns an HTML string with the expressions replaced by their corresponding values.

Here‘s a very basic example:

var source = "<p>Hello, my name is {{name}}. I am from {{hometown}}.</p>";
var template = Handlebars.compile(source);

var data = { name: "Nils", hometown: "Stockholm" };
var result = template(data);
// Returns "<p>Hello, my name is Nils. I am from Stockholm.</p>"

The generated template function looks something like this under the hood:

function (context, options) {
  // ...
  return "<p>Hello, my name is " + context.name + ".I am from " + context.hometown + ".</p>";
}  

As you can see, the expressions have been replaced with simple property lookups on the context object. This makes rendering a template extremely fast, since there‘s no complex logic or computation involved, just string concatenation.

What‘s even more powerful is that Handlebars compiles all the templates ahead of time, so the template function is generated only once and then reused for every render. This is a significant performance boost compared to template engines that have to parse and compile the template on every render.

Handlebars usage and popularity

Handlebars has seen significant adoption over the years and remains a popular choice for many developers. Let‘s look at some stats:

• Handlebars is used by over 1.5 million repositories on GitHub
• It‘s downloaded over 25 million times per month on npm
• Question views for Handlebars on Stack Overflow have grown by 50% year over year
• In the 2020 State of JS survey, 14.6% of respondents reported using Handlebars

Handlebars downloads per month on npm

While it may not have the buzz and hype of newer tools, Handlebars has stood the test of time and continues to be a reliable and efficient solution for many teams and projects.

When to use Handlebars

So when is Handlebars a good choice for your project? Here are some scenarios where it shines:

• You need a quick and easy templating solution for rendering dynamic content
• Your application is primarily server-rendered and you‘re just sprinkling in some dynamic elements
• You want to keep your front-end code simple and avoid the overhead and complexity of a larger framework
• Performance is critical and you need the fastest possible rendering time

On the flip side, Handlebars may not be the best fit if:

• You‘re building a highly interactive, client-side application with lots of real-time updates
• You need a full component system with robust state management and data binding
• Your team is already invested in another framework like React or Vue

Ultimately, the choice of templating engine or framework depends on the specific needs and constraints of your project. But if you want a tried-and-true solution that‘s simple, fast, and easy to learn, Handlebars is definitely worth considering.

Getting started with Handlebars

Enough theory, let‘s dive into some code! To start using Handlebars, first install it via npm:

npm install handlebars

Or include it directly in your page:

<script src="https://cdn.jsdelivr.net/npm/handlebars@latest/dist/handlebars.js"></script>

Now let‘s define a simple template:

<script id="entry-template" type="text/x-handlebars-template">
  <div class="entry">

    <div class="body">
      {{body}}
    </div>
  </div>
</script>

To render this template, we first need to compile it into a function using Handlebars.compile:

var source = document.getElementById("entry-template").innerHTML;
var template = Handlebars.compile(source);

Then we can execute the template function with a context object to get the final HTML:

var context = {
  title: "My New Post",
  body: "This is my first post!"
};

var html = template(context);
// Returns "<div class="entry"><div class="body">This is my first post!</div></div>"

Finally, we can insert the HTML into the page:

document.getElementById("entries").innerHTML = html;

And that‘s it! We‘ve successfully rendered a dynamic template with Handlebars.

Real-world example: Handlebars with Node.js and Express

Let‘s look at a more realistic example of using Handlebars in a Node.js web application with the Express framework.

First, install the express-handlebars package:

npm install express-handlebars

Then, configure Express to use Handlebars as its view engine:

const express = require(‘express‘);
const exphbs = require(‘express-handlebars‘);

const app = express();

app.engine(‘handlebars‘, exphbs());
app.set(‘view engine‘, ‘handlebars‘);

Create a views directory and put your Handlebars templates in it, with a .handlebars file extension. For example:

views/
  layouts/
    main.handlebars
  partials/
    header.handlebars
    footer.handlebars
  index.handlebars

Your main.handlebars layout file might look like this:

<!DOCTYPE html>
<html>
<head>
  <title>My App</title>
</head>
<body>
  {{>header}}
  {{{body}}}
  {{>footer}}
</body>
</html>

The {{{body}}} expression will be replaced with the contents of the specific view being rendered.

An index.handlebars view might look like:

<ul>
  {{#each items}}
    <li>{{this}}</li>
  {{/each}}
</ul>

To render this view, set up a route in Express:

app.get(‘/‘, (req, res) => {
  res.render(‘index‘, {
    title: ‘My App‘,
    items: [‘Item 1‘, ‘Item 2‘, ‘Item 3‘]
  });
});

The res.render function takes the name of the view to render and an object containing the data to pass to the view.

Start your Express app and navigate to http://localhost:3000 to see the rendered view:

<!DOCTYPE html>  
<html>
<head>
  <title>My App</title>
</head>
<body>
  <header>...</header>


  <ul>
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
  </ul>

  <footer>...</footer>
</body>
</html>

This is just a basic example, but it demonstrates how easy it is to integrate Handlebars into a Node.js application and use it to render dynamic views.

Conclusion

Handlebars is a powerful and versatile templating engine that has stood the test of time. Its simple syntax, excellent performance, and extensive feature set make it a great choice for rendering dynamic content on the web.

In this tutorial, we‘ve covered the basics of using Handlebars, from the underlying concepts to real-world examples. I encourage you to explore the official Handlebars documentation to learn more about its advanced features and helpers.

As a professional developer, I appreciate tools like Handlebars that are focused, reliable, and easy to integrate into my existing workflow. While it may not be the right choice for every project, Handlebars is definitely a valuable asset in my front-end toolbox.

So go forth and start building dynamic, interactive web applications with Handlebars! And if you have any questions or comments, feel free to reach out. Happy coding!