VueJS - Vue Filters

Creating and Using Filters

Filters in VueJS are a simple way to format data displayed to the user. They can be used in mustache interpolations and v-bind expressions. This guide covers how to create and use filters in your VueJS applications.

Creating a Filter

To create a filter, define a function that takes a value and returns the formatted value:

// filters/capitalize.js
export function capitalize(value) {
  if (!value) return '';
  value = value.toString();
  return value.charAt(0).toUpperCase() + value.slice(1);
}
                

Using a Filter Locally

To use the filter locally in a component, import it and add it to the component's filters option:

// MyComponent.vue



                

Using a Filter Globally

To use the filter globally, register it with Vue in your main.js file:

// main.js
import Vue from 'vue';
import App from './App.vue';
import { capitalize } from './filters/capitalize';

Vue.filter('capitalize', capitalize);

new Vue({
  render: h => h(App),
}).$mount('#app');
                

Chaining Filters

You can chain multiple filters together in a template expression:

// filters/reverse.js
export function reverse(value) {
  if (!value) return '';
  return value.split('').reverse().join('');
}

// MyComponent.vue



                

Common Use Cases for Filters

Filters are commonly used for:

• Text transformation (e.g., capitalization, truncation)
• Formatting dates and numbers
• Localization of strings
• Displaying default values

// filters/date.js
export function formatDate(value) {
  if (!value) return '';
  const date = new Date(value);
  return date.toLocaleDateString();
}

// MyComponent.vue



                

Best Practices

Follow these best practices when creating and using filters:

• Keep Filters Simple: Ensure that your filters are focused on a single responsibility.
• Use Filters for Presentation Logic: Filters should be used for formatting data for display, not for complex business logic.
• Document Filters: Provide clear documentation for your filters to ensure they are easy to understand and use.
• Test Filters Thoroughly: Test your filters to ensure they work correctly with various input values.
• Handle Edge Cases: Ensure that your filters handle edge cases, such as null or undefined values, gracefully.

Summary

This guide provided an overview of creating and using filters in VueJS, including defining filters, using them locally and globally, chaining filters, common use cases, and best practices. By understanding and utilizing these techniques, you can enhance the presentation of your VueJS applications and create reusable, modular code.