AngularJS: Is ng-click "a good practice"? Why is there no ng-{event} in AngularJS?

Question

I just started to learn AngularJS and struggle with some concepts of AngularJS. It would be great if somebody could explain me some points...

1. I understand that ng-click is technically not the same as onclick (see here), but both are placed in the markup. I thought that would be a "bad practice"? Why is this one of the core concepts of AngularJS, if most people say this is "bad"? I thought it would be better to select the DOM element from JavaScript and not to place logic in the markup.

2. If ng-click is the right way to react to click events in AngularJS what should I do with other DOM events? I see that there are several other directives like ng-mouseover, but not all DOM events have a AngularJS equivalent. How would I handle a 'drop' event in AngularJS (hence in the AngularJS way - not the normal way)? To be clear: I want to drag a file into my webapp.

Thank you very much, Pipo

Answer 1

Why is this one of the core concepts of AngularJS, if most people say this is "bad"?

Well, people who really like Unobtrusive JavaScript might say it is bad. Angularians (and those with a flex background) see value in the more declarative approach.

"Angular is built around the belief that declarative code is better than imperative when it comes to building UIs and wiring software components together... By declaratively describing how the UI should change as your application state changes, you are freed from low level DOM manipulation tasks. -- Overview doc

See also Don't the data attribute options used in Bootstrap, Angular.js, and Ember.js conflict with Unobtrusive Javascript principles?

what should I do with other DOM events?

Write your own directives to listen for them (or find one that someone else has already written). Angular gives you the power to extend what the browser can do -- by writing your own directives.

Update: in the comments below, Tim Stewart mentions AngularUI's ui-event, which lets you bind a callback to any event not natively supported by Angular.

Answer 2

By nature, Angular requires elements in the markup in order to function properly. Further, those elements must be "compiled" each time they change, for the most part. So, it's already somewhat "obtrusive" irrespective of the JavaScript. You can't simply replace the markup, and have everything auto-bound for you like you can with something like jQuery.

Strictly speaking, unobtrusive JavaScript: 1. separates structure and behavior, in order to make your code cleaner and script maintenance easier 2. preempts browser incompatibilities 3. works with a clean, semantic HTML layer (Wikipedia)

That's not Angular, for sure. In order to achieve the two-way binding on everything, they chose to make custom binding points in the DOM, as opposed to using a class name or ID the way that jQuery would do. (A somewhat non-standard approach, but it obviously works.)

But the real way to think of it is this: Basically each controlled section of your markup is not really straight HTML anymore anyway. It's really more of a template now, and as such requires interaction with the engine that is preparing it for rendering. As such, the traditional rules of unobtrusiveness don't really apply... (FWIW, I'm a huge fan/user of the jQuery.on() function to bind elements to events automatically when the element is added to the page. Very clean and flexible, IMHO, and I do wish there was a similar mechanism in Angular. I like adding a class to items in multiple locations on the page that invoke the same event handler automatically. Having a single place to go change code is a good thing. but I digress...)

For me, the bigger issue is that of progressive design. Does the web page work without JavaScript enabled at all? Does anyone really care about that? Hmmm...