Using Ember.js, how do I run some JS after a view is rendered?

Ember 2.x: View is deprecated, use component instead

You have to understand the component's lifecycle to know when does certain things happen.

As components are rendered, re-rendered and finally removed, Ember provides lifecycle hooks that allow you to run code at specific times in a component's life.

https://guides.emberjs.com/v2.6.0/components/the-component-lifecycle/

Generally, didInsertElement is a great place to integrate with 3rd-party libraries.

This hook guarantees two (2) things,

1. The component's element has been both created and inserted into the DOM.
2. The component's element is accessible via the component's $() method.

In you need JavaScript to run whenever the attributes change

Run your code inside didRender hook.

Once again, please read the lifecycle documentation above for more information

You can also use afterRender method

didInsertElement: function () {
Ember.run.scheduleOnce('afterRender', this, function () {
     //Put your code here what you want to do after render of a view
    });
}

You need to override didInsertElement as it's "Called when the element of the view has been inserted into the DOM. Override this function to do any set up that requires an element in the document body."

Inside the didInsertElement callback, you can use this.$() to get a jQuery object for the view's element.

Reference: https://github.com/emberjs/ember.js/blob/master/packages/ember-views/lib/views/view.js

Starting with Ember 3.13, you can use components that inherit from Glimmer, and this example below shows what that could look like:

import Component from '@glimmer/component';
import { action } from '@ember/object';

/* global jQuery */

export default class MyOctaneComponent extends Component {
  @action configureSorting(element) {
    jQuery(element).sortable();
  }
}

<div {{did-insert this.configureSorting}}>
  <span>1</span>
  <span>2</span>
  <span>3</span>
</div>

These view style components don't have lifecycle hooks directly, instead, you can use render-modifiers to attach a function. Unofficial introduction to modifiers can be found here

The benefit of this is that, it's clearer what the responsibilities of the template are and become.

Here is a runnable codesandbox if you want to play around with this: https://codesandbox.io/s/octane-starter-ftt8s