how to add default modifier in jane

2 min read 30-01-2025

Jane, a powerful and flexible templating engine, allows you to create reusable components and enhance your code's readability. One way to achieve this is by using default modifiers. Default modifiers let you pre-set values for attributes in your templates, simplifying the process of rendering elements with common settings. This article will guide you through the process of adding default modifiers in Jane.

Understanding Modifiers in Jane

Before diving into default modifiers, let's quickly review how standard modifiers work in Jane. Modifiers are essentially functions that transform or enhance the output of a template variable. They are applied using the pipe symbol (|). For example, if you have a variable name and want to uppercase it, you might use the uppercase modifier:

{{ name | uppercase }}

Implementing Default Modifiers

Jane doesn't have a built-in mechanism for directly defining "default modifiers." The concept of a "default modifier" needs to be implemented using custom functions or pre-processing steps. Here are a few approaches:

1. Using a Helper Function

The most common and flexible method is creating a helper function. This function encapsulates the default modification logic. You'd call this helper function within your templates.

Example: Let's say you want to always apply a trim and lowercase modifier to a username variable.

// In your Jane configuration or a separate helper file:
const jane = require('jane');

jane.addHelpers({
  formatUsername: function(username) {
    return username.trim().toLowerCase();
  }
});

// In your Jane template:
{{ formatUsername(username) }}

This approach keeps your template cleaner and more readable. The complexity of the default modification is hidden within the helper function.

2. Pre-Processing the Data

Another approach is to modify the data before it's passed to the Jane template engine. This involves altering the context object in your application logic.

Example:

// Before rendering the template:
const context = {
  username: "  John Doe  ",
  // ... other data
};

context.username = context.username.trim().toLowerCase(); // Pre-process the username

// Now render the template with the pre-processed data:
jane.render(template, context);

This is less elegant than using a helper function, especially if you have many default modifications to apply. It couples your template logic with data preparation.

3. Custom Filters (Advanced)

For more advanced users familiar with Jane's internals, you could potentially create a custom filter that applies your default modifications. This requires a deeper understanding of Jane's plugin system.

Best Practices

Keep it Simple: Favor helper functions for most cases. They improve readability and maintainability.
Consistency: Apply consistent naming conventions to your helper functions.
Testing: Thoroughly test your default modification logic to ensure it behaves as expected in various scenarios.

Conclusion

While Jane doesn't directly support "default modifiers" as a built-in feature, you can effectively achieve the same result using helper functions or data pre-processing. Choosing the best method depends on your project's complexity and your preferred coding style. By applying these techniques, you can create more maintainable and reusable templates in your Jane projects. Remember to choose the approach that best suits your project's needs and maintainability goals. Using helper functions generally leads to cleaner and more readable code.