**Handlebars** is a template engine that can generate HTML using JavaScript code. The template engine is very easy to learn and use due to its syntax and the *built-in* helpers it provides. Handlebars can be included in a project using the CDN link in the `<script>` tag:

```html
<script
src="https://cdnjs.cloudflare.com/ajax/libs/handlebars.js/4.1.2/handlebars.min.js">
</script>
```

To get a link for the latest Handlebars version, visit #key# this link: https://cdnjs.com/ #key#.

# Creating and executing a simple template

1. Declare a template in the HTML file. Handlebars expressions are put into double curly braces ``{{expr}}`` for HTML-escaped content; otherwise, use triple curly brackets ``{{{expr}}}`` to avoid HTML-escaping.

In the JavaScript file:

2. Get this template using `document.getElementById()`.
3. Compile it using `Handlebars.compile()`.
4. Since a template is meaningless without a context, an object containing the required variables is created. This data is known as the **​context**.
5. Generate the HTML with `template(context)`.
6. Insert the generated HTML into​ an HTML element.

<!DOCTYPE html>
<html>

<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/handlebars.js/4.1.2/handlebars.min.js"></script>
</head>

<body>
  
  <div id="content"></div>
  
  
  <script id="myTemplate" type="text/x-handlebars-template">
    <div>
      <h1>{{title}}</h1>
      <p>{{body}}</p>
    </div>
  </script>
  
</body>

</html>

window.onload = function(){
  // Get the template from HTML file:
  var source = document.getElementById('myTemplate').innerHTML;

  // Compile the template:
  var template = Handlebars.compile(source);

  // Create the context:
  var context = {title: "My New Post", body: "This is my first post!"};

  // Generate HTML:
  var html = template(context);

  // Insert rendered template into HTML:
  document.getElementById('content').innerHTML = html;
}


codemirror

# Helpers

Handlebars have built-in helpers for common tasks, such as `if` or `else` condition blocks. The name of the helper is preceded by a `#` in the starting tag, and by a `/` in the closing tag -- instead of using `<>` for tags, curly braces are used.

## #if helper

The `#if` helper takes in one argument and renders the HTML inside the helper block if the passed parameter is not: `false`, `undefined`, `null`, `""`, `[]` or `0`; otherwise, the `{{else}}` block executes.

>The `{{else}}` tag is written inside the `#if` helper; it does not require a closing tag.

## #each helper

The `#each` helper is used to iterate over a list, which is passed as the argument. Each item of the list, as well as its attributes, can be accessed using the `this` keyword.

The code below demonstrates how to use `#if`, `{{else}}`, and `#each`.

<!DOCTYPE html>
<html>

<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/handlebars.js/4.1.2/handlebars.min.js"></script>
</head>

<body>
  
  <div id="content"></div>
  
  
  <script id="myTemplate" type="text/x-handlebars-template">
    <div>
        {{#each posts}}
          <h1>{{this.title}}<h1>
          {{#if this.content}}
              <h3>{{this.content}}</h3>
          {{else}}
              <h3>No content found!</h3>
          {{/if}}
        {{/each}}
    </div>
  </script>
  
</body>

</html>

What are Handlebars in JavaScript?

Handlebars is a JavaScript template engine for generating HTML, supporting expressions, and built-in helpers for conditional logic and iterating over lists.