Handlebars.js vs Nunjucks: What are the differences?

Introduction:

Handlebars.js and Nunjucks are templating engines that allow for dynamic content rendering in web applications. While they have similar functionalities, there are several key differences between the two.

1. Syntax: Handlebars.js uses double curly braces {{ }} to denote variables and expressions, while Nunjucks uses double curly braces with a percentage sign {{% %}} for the same purpose. This difference in syntax can affect the readability and familiarity of the templating engine for developers.

2. Template Inheritance: Nunjucks provides an inheritance feature that allows for the creation of reusable templates with defined blocks that can be extended or overridden in child templates. Handlebars.js does not have built-in template inheritance, which can make code organization and reuse more challenging.

3. Filters and Extensions: Nunjucks offers a wide range of built-in filters and extensions, which provide additional functionalities such as formatting, manipulating data, and customizing the template engine. Handlebars.js, on the other hand, has a more limited set of built-in helpers, and extending its functionalities requires writing custom helpers.

4. Whitespace Control: Nunjucks provides finer control over whitespace handling within templates. It allows trimming leading and trailing whitespace and specifying custom whitespace control rules. Handlebars.js, on the other hand, does not offer such explicit control over whitespace, which might lead to unexpected rendering results in some scenarios.

5. Async Support: Nunjucks has built-in support for asynchronous operations. It allows for the use of asynchronous filters and functions, enabling dynamic content retrieval from external resources. Handlebars.js, however, does not provide native support for asynchronous operations, requiring developers to implement workarounds or rely on external libraries.

6. Error Handling and Debugging: Nunjucks provides detailed error messages and stack traces, making it easier to identify and debug issues within templates. Handlebars.js, on the other hand, provides less detailed error messages, which might make troubleshooting more time-consuming and challenging.

In summary, Handlebars.js and Nunjucks differ in syntax, template inheritance capabilities, filter and extension offerings, whitespace control, async support, and error handling and debugging features. These differences should be considered when choosing a templating engine for a web application.