Expressions in Handlebars

Handlebars is a popular templating engine for web development. It allows developers to create dynamic HTML documents using reusable templates. One of the powerful features of Handlebars is its ability to use expressions, which allow you to generate dynamic content based on data passed into the template. In this article, we will explore how to use Handlebars Expressions in your code.

Handlebars Expressions are used to evaluate an expression and return a value that can be used in the template. They start with a double curly bracket "{{" followed by the expression itself and ending with a double curly bracket "}}". Here is an example:

{{ name }}

This code will output the value of the variable name. The variable can be passed into the template using data attributes. For example:

<h1>Hello, {{ name }}!</h1>

In this example, we are passing in a variable called name and using it as the value of the string "Hello, ". The output will be "Hello, John!" if the name variable is set to "John".

Handlebars Expressions can also be used to perform calculations on variables. For example:

{{ product.price * 1.2 }}

This code will multiply the value of the variable product.price by 1.2 and return the result. The output will be "18.00" if the price is "15".

Handlebars Expressions can also be used to compare variables using the "===" operator. For example:

{{ product.category == 'electronics' }}

This code will evaluate whether the value of the variable product.category is equal to "electronics". The output will be true if the value is "electronics" and false if it is not.

Handlebars Expressions can also be used to access nested variables. For example:

{{ cart.items[0].name }}

This code will access the first item in the cart.items array and return its value for the variable name. The output will be "iPhone 12" if the cart has one item with a name of "iPhone 12".

Handlebars Expressions can also be used to loop through arrays using the "{{#}}" and "{{/}}}" syntax. For example:

<ul>
    {{#cart.items}}
        <li>{{name}} - {{price}}</li>
    {{/}}}
</ul>

This code will loop through the cart.items array and output a list item for each item with its name and price. The output will be:

<ul>
    <li>iPhone 12 - 999.00</li>
    <li>iPad Pro - 799.00</li>
</ul>

Handlebars Expressions can also be used to conditionally render content based on the value of a variable. For example:

<div class="promo">
    {{#isPromo}}
        <p>{{message}}</p>
    {{/}}}
</div>

This code will check if the isPromo variable is true and output a paragraph with its value for the message variable. The output will be:

<div class="promo">
    <p>Limited time offer! Buy now and save 20%.</p>
</div>

In conclusion, Handlebars Expressions are a powerful tool in web development that allow you to create dynamic HTML documents using reusable templates. They can be used for calculations, comparisons, accessing nested variables, looping through arrays, and conditionally rendering content based on the value of a variable. By mastering the use of Handlebars Expressions, you can create more efficient and powerful code that will make your web applications even better.