What is ember-modifier?
The ember-modifier package provides a way to create reusable, composable, and encapsulated behavior for DOM elements in Ember.js applications. It allows developers to define custom modifiers that can be applied to elements in templates, enabling a clean separation of concerns and enhancing code maintainability.
What are ember-modifier's main functionalities?
Creating a Simple Modifier
This feature demonstrates how to create a simple modifier that focuses an input element when it is inserted into the DOM. The `focusInput` modifier is defined and then applied to an input element in a template.
```javascript
// app/modifiers/focus-input.js
import { modifier } from 'ember-modifier';
export default modifier(function focusInput(element) {
element.focus();
});
// Usage in a template
<input {{focus-input}} />
```
Modifier with Arguments
This feature shows how to create a modifier that accepts arguments. The `setAttribute` modifier takes an attribute name and value as arguments and sets the attribute on the element.
```javascript
// app/modifiers/set-attribute.js
import { modifier } from 'ember-modifier';
export default modifier(function setAttribute(element, [attribute, value]) {
element.setAttribute(attribute, value);
});
// Usage in a template
<div {{set-attribute 'data-test' 'example'}}></div>
```
Modifier with Cleanup
This feature illustrates how to create a modifier that adds an event listener to an element and cleans up the listener when the element is removed from the DOM. The `addEventListener` modifier adds a specified event listener and returns a cleanup function to remove the listener.
```javascript
// app/modifiers/add-event-listener.js
import { modifier } from 'ember-modifier';
export default modifier(function addEventListener(element, [event, handler]) {
element.addEventListener(event, handler);
return () => {
element.removeEventListener(event, handler);
};
});
// Usage in a template
<button {{add-event-listener 'click' this.handleClick}}>Click me</button>
```
Other packages similar to ember-modifier
ember-on-modifier
The ember-on-modifier package provides a simple way to add event listeners to elements in Ember.js templates using the `{{on}}` modifier. It is similar to the `addEventListener` feature of ember-modifier but is more focused on handling events in a declarative manner. While ember-on-modifier is great for straightforward event handling, ember-modifier offers more flexibility for creating complex and reusable behaviors.