I have been developing an advanced web-based GUI in AngularJS. Recently, I decided to use the call document.getElementsByClassName() (I hate using element collecting methods, but here I had to use one) and my boss flipped his lid for accessing the document element. He says that I "need to use only Angular calls for everything", even for element collection! Is there an "Angular way" to collect elements by class name? If so, which way is better to use within the Angular framework? Please provide reasons why. Thanks!
UPDATE: Why I need to use an element collector...
So, I really wish I didn't have to do this, but I do...
I am using a third-party directive that I found online called the Bootstrap DateTimePicker. Its pretty cool and very nice looking, yet it might have a bug...
First, I make a directive bound to an attribute, stating that the element I pass in is meant to be a "DateTimePicker". I then pass that element to the DateTimePicker function.
When invoked, this function creates a new div with absolute positioning and appends it to the body of the page.
Now, I open a dialog in my GUI that has a table in it. On each row of the table, I have two DateTimePickers: one for end-date and one for start-date.
My problem is that, once I leave my screen and the elements which the DateTimePickers were bound to are destroyed, the DateTimePickers still remain! If I open the dialog box again, it creates a ton more of these divs as well!
Until I could determine a true solution to this issue, I decided to use the element collector as a temporary quick-fix. I grab all of the elements with the datetimepicker class and perform a:
elem[i].parentNode.removeChild(elem[i]);
Not having your exact use case but knowing that you are attempting to aggregate elements by class name in your controller makes me agree with you boss. Think of the controller as an object which exposes data and and services to your declarative html page. The data is bound into the markup for presentation and possible modification. THe services are usually wrapped in functions on your controller which are then tied to event handling directives like ng-click or ng-change. These services should operate exclusively on your data and never touch the DOM. If you need to modify a DOM element in your declarative markup then that should be done through directives like ng-class etc.
In any case, It would be useful to know what you are trying to accomplish so as to give you a better idea of the "angular way" to approach the problem.
Well, I have my answer. This does not solve the question "Grab all elements with a certain class name without touching the document element" yet it does solve my problem and eliminates my need to use document.getElementsByClassName.
First of all, it turns out that every element using the DateTimePicker directive have an element.datetimepicker("remove") function.
I use a directive for each DateTimePicker:
components.directive('DateTimePicker', function() {
// Requires bootstrap-datetimestamp.js
return {
restrict: 'E',
replace: true,
scope: {
dateTimeField: '='
},
template:
'<div>' +
'<input type="text" readonly data-date-format="yyyy-mm-ddThh:ii:ssZ" data-date-time required/>'+
'</div>',
link: function(scope, element, attrs, ngModel)
{
var input = element.find('input');
input.
datetimepicker(
{
//stuff
})
.on('changeDate', function(ev)
{
//more stuff
});
...
Directive drastically shortened for the sake of your eyeballs...
I then need to remove the DateTimePicker and the input it is bound to from the DOM on destruction of the dialog box that the input is a child of. To do so, I added this to my directive:
scope.$on("$destroy",function handleDestroyEvent()
{
input.datetimepicker("remove");
input = null;
});
And it works! The DateTimePicker gets removed, the DateTimePicker's handles to the input are cleaned up, and I've marked my input for the GC! WooHoo! Thanks everybody!
If you include jQuery in your project before AngularJS, Angular will use jQuery instead of jqLite for the angular.element function. This means you should be able to use jQuery's selectors for finding / referencing DOM elements.
Related
I'm creating a custom Angular directive for a slide in menu which needs to watch a couple of attributes and one of those attributes needs to be two way bound to the main controller scope (sometimes). However, sometimes the attribute will not be added by the developer so it needs to be added automatically and set to the default (false). So, the directive can be used like this.
<slide-menu position="right" is-open="menuIsOpen"></slide-menu>
or like this:
<slide-menu></slide-menu>
When used the first way the main controller will be able to open and close the menu by changing the value of the boolean $scope.menuIsOpen.
When used without supplying the is-open attribute it should default to false and is obviously used internally and by a child toggle directive.
An additional complication is that whether the attribute is supplied by the developer or not it should exist in the DOM. so in the second example above the directive would set itself to false by default and add the attribute is-open="false" to the DOM?
The reason for requiring is-open="false/true" in the DOM at all times is that the menu is actually operated using CSS tansitions which use the following selector:
slide-menu[is-active="true"]{
// Slide the menu in using transforms/transitions
}
There is a jsfiddle here which shows how far I have got.
http://jsfiddle.net/jonhobbs/gEPvE/
Obviously it doesn't work, but it shows how I have tried to set a default and how I have tried to use # and & on the isolated scope for a one time binding (the menu position) and a 2 way bound expression for the is-open variable.
I'm clearly a long way from achieving what I need but any advice would really be appreciated.
Have a look at this fiddle http://jsfiddle.net/gEPvE/38/
I took the one you started and updated it to act like you specified.
You can make a two way binding value optional by adding a ? on the scope definition.
Like this
{
scope: {
'isOpen':'=?'
}
}
Now the is-open attribute is optional.
Then you can set the default value in the directive controller, like you had started to do.
Next, in order to synchronize the DOM attribute with the scope value you can use $watch.
$scope.$watch('isOpen', function(val) {
$element.attr('is-open', val);
});
Finally, I changed the second 'slideMenuToggle' directive to wrap/transclude its element in order to add an ng-click handler. This is mainly to avoid any nastiness with calling $scope.$apply yourself.
Let me know if that works for you.
EDIT
Answering your question in the comment, you can pass a value directly without having it be bound to the scope, you just need to wrap the value in quotes.
For example
<div ng-controller='ctrl'>
<hello world='imOnScope'></hello>
</div>
Assuming 'hello' is a directive with a scope of 'world': '=?' then angular will assign a reference to the parent scope's 'imOnScope' object to the directive's $scope.world member, allowing a two way binding scenario.
To just provide a value directly you may do something like this
<div ng-controller="ctrl">
<hello world="'directValue'"></hello>
</div>
In this scenario angular will just assign 'directValue' to the directive's $scope.world member.
You need to add ngTouch to your module.
var app = angular.module('app', ['ngTouch']);
And add this script:
http://ajax.googleapis.com/ajax/libs/angularjs/1.2.1/angular-touch.js
The reason for requiring is-open="false/true" in the DOM at all times
is that the menu is actually operated using CSS tansitions which use
the following selector
Forcing directive attributes to be appropriate for css selectors is terrible idea. As you correctly stated, they are for developers. So add a class to the element dynamically.
It seems that you're misusing &, it would be ok to set up a callback, but since you don't do this, in its current state you can end up with one-way # with confidence.
I guess it can be something like this (just added ngTouch and ng-controller for parent scope).
You could replace
$scope.watch('isOpen', function () {
$element.toggleClass('opened', $scope.isOpen);
});
with
$scope.watch('isOpen', function () {
$attrs.isOpen = !!$scope.isOpen;
});
and get the behaviour you're asking for, easy as that. Ok, it is boolean now, and it reflects the scope, and you can use [is-open=true] selector. But guess what will happen with your binding? Broken. Fortunately, you can do
$scope.watch('isOpen', function () {
$element.attr('is-open', !!$scope.isOpen);
});
instead. Voila, we tricked Angular because it doesn't look after jqlite. But what will will happen with the binding when the directive will be re-compiled for any reason? Again, isOpen's binding is non-existing 'true' or 'false' scope variable. Broken.
It seems that getting an element in AngularJS is a bad idea, i.e. doing something like:
$('.myElement')
in say, a controller is not an angular way of doing things.
Now my question is, how should I get something in angular?
Right now, what I'm doing (and is an accepted way of doing it) is by watching a variable, and my directive does something based on it.
scope.$watch('varToWatch', function (varToWatch) {
if(attrs.id == varToWatch)
{
//Run my Directive specific code
}
});
However, while this particular design works for most cases, watch is an expensive operation, and having lots of directives watching can really slow down your application.
TL:DR - What is an angular way of getting a directive based on a variable on the directive? (like the one above)?
If you want to get/set values you don't need to fetch the element using jQuery. Angular data binding is the way to do it.
directives is the way to go if you want to do animations or any kind of element attributes and DOM manipulation.
Your code is basically right; the directive should watch something in the $scope and perform it's logic when that thing changes. Yes, watch statements are expensive, and that is a problem once your number of watches start to approach ~2000.
Looking at your code though, I see one problem:
The variable $scope.varToWatch references an id in the template.
When this variable changes, you want something to happen to the element which has this id.
The problem here is in the first point: The controller should know nothing about the DOM, including the id of any element. You should find another way to handle this, for example:
<div my-directive="one"> ... </div>
<div my-directive="two"> ... </div>
<div my-directive="three"> ... </div>
...etc
And in your directive:
scope.$watch('varToWatch', function (varToWatch) {
if(attrs.myDirective == varToWatch)
{
// Run my Directive specific code
}
});
You are very vague as to what you're trying to achieve, but I'll try to answer in context of your last comment.
I have a lot of the same directives (therefore the code will run on all of them), but I need to get only one directive from the lot.
You talk a lot about getting the right element. The directive element is passed to the link function in the directive. If you are not using this element (or children of it) directly, but rather trying to search for the element you want somehow, you are most likely approaching the problem the wrong way.
There are several ways to solve this, I'm sure. If you're thinking about animations, there is already support for that in Angular, so please don't try reinvent the wheel yourself. For other logic, here are two suggestions:
Secondary directive
If the logic you want to apply to this directive is generic, i.e. it could be applied to other directives in your application, you could create a new directive which works together with directives. You can set prioritization in directive in order to control which directive is executed first.
<main-directive ... helper-directive="{{condition_for_applying_logic}}"></main-directive>
jsFiddle example
Expanding main directive
If the logic is tightly coupled to this directive, you can just create a new attribute, either dynamic or static, and bind to it in the directive. Instead of checking 'attrs.id == varToWatch', you check if $scope.apply-logic === 'true' and apply the logic then.
<main-directive ...></main-directive> <!-- Not applied here -->
<main-directive apply-logic="true" ...></main-directive> <!-- Applied here -->
<main-directive apply-logic="{{some.varOnScope}}"...></main-directive> <!-- Conditional -->
Please comment if something is unclear.
It's pretty common thing, like if you click on inbox here here on stackoverflow. I'll be calling that dialog or whatever gets opened a thing.
Now there are two ways I know of to deal with this,
you create an invisible overlay where only the element you opened
has bigger zindex, and you close your thing by clicking on the
overlay
click event on the document, and you check upon clicking whether you clicked on your thing or outside it, in which case you close your thing.
In either case I'd ideally like to use ng-class to add/remove class that would show/hide the thing.
Now how would I do this with angular, so it could be used on any component(thing) I might add. It's not like I have single modal, I might have quite a few different components, with different html structure, positioning and stuff.
Which approach would be better, document event, overlay or something completely else?
Since angular doesn't really have any reference to dom, document approach could be a problem, right, since I can't quite check whether I'm clicking on the thing element? Unless I'd give every thing the same class..
Overlay approach on the other hand doesn't require any reference to dom elements.
Both approaches would need a unique var at rootScope for that ng-class to work.. which bring the question whether to use ng-class or something custom..
Anyway just throwing my ideas out there, maybe I'm thinking about it wrong from the beginning, has anyone dealt with this before?
The way I've tackled things like this before is using inheritedData to communicate to the click handler whether it's in or out of the thing:
In the custom directive for the thing, add a data variable to the element, using jqLite data, say element.data('myThing',true) . If you want to distinguish between multiple instances of the the thing, you might need to use some uniquely generated key.
In the same custom directive, in a click event handler on document.body, you can check angular.element(event.target).inheritedData('myThing')
An example directive that uses this technique is below
app.directive('thing', function($document,$window) {
return {
restrict: 'E',
template: '<div><span>Inner thing</span></div>',
replace: true,
link: function(scope,element) {
element.data('thing',true);
angular.element($document[0].body).on('click',function(e) {
var inThing = angular.element(e.target).inheritedData('thing');
if (inThing) {
$window.alert('in');
} else {
$window.alert('out');
}
})
}
}
});
and can be seen in this Plunker http://plnkr.co/edit/bRDLcLoesM7Z0BIxKxYu?p=preview
I've been playing around a bit with this slick jQuery datpicker and wanted to wrap it up as a directive that I could use inside my angular app. The code for the directive is very simple for right now:
directive('datePicker', function() {
return {
restrict: 'E',
template: '<input type="text" class="topcoat-text-input--large full" placeholder="Select Date">',
link: function (scope, element, attrs) {
element.pickadate();
}
}
As you can see I'm simply targeting the element parameter with the necessary pickadate() jQuery call. The input is properly being targeted as when I click on it I am provided with the datepicker interface and can interact with it no problem. However, when I select a date no information is being populated into the input element. Am I missing something obvious that will allow the date being selected from the control to set the value of the input?
I've done a little bit of debugging and in the link function the element parameter seems to be wrapping the actual input in some way (there seems to be a childNodes array property that holds the <input> tag). Could this be why I'm getting the popup for the picker but the selected value isn't being set as the input's value?
element is the original element in your markup. By default it is not replaced and template is used for innerHtml.
You could use replace:true option in directive or element.find('input').pickadate()
Either of these should resolve visual issue of seeing date. One important thing to note however when you use ng-model and change a value from external code like a jQuery plugin, will need to use the plugin select ( or whatever it is called in pluginAPI) callback to trigger scope.$apply(). This infomrs angular a change was made from code external to angular and to update internals
I suppose you should add replace: true to your directive definition - Angular is targeting the <date-picker> directive element instead of the input.
Instead you can also try this: element.children().first().pickadate();
I wrote an attribute restricted Angular directive (restrict:'a') that adds features to textarea. It makes no sense to apply it to any other type of element.
Adding a if (element.nodeName == 'TEXTAREA') { is really dirty and unreliable.
I tried to add require: textarea to it but it does not work and I get this error: Error: No controller: textarea
Question: Is there any cleaner way to properly apply this restriction?
EDIT: Additional constraint following the first answer.
I want to avoid using a template in this directive as I want to be able to use several directive of this type. Here is an example of what I'd like:
<textarea splittable shared mergeable></textarea>
When using your own directive (eg my-textarea) with restrict: 'E', replace: true, any additional attributes will get carried over to the root-element of the directive, even other attribute directives. So:
<my-textarea splittable class="foobar"></my-textarea>
could be rendered as:
<textarea splittable="" class="foobar"></textarea>
with splittable being executed.
demo: http://jsfiddle.net/LMq3M/
So I think using your own directive is realy the cleanest way to handle this.
In my opinion there is no need to add such controls as they just tend to add complex code when the real issue is human error.
Just document what the purpose and usage is for the directive.
The idea is you give your directive a unique name, like myDirective and you can use it in HTML as such.
<body>
<my-directive></my-directive>
</body>
The directive will replace the tag with the template you provided in the directive controller. Which could be in your case a simple textarea element with added properties.
I recommend watching this video to clearly grasp the concept of directives.
http://www.youtube.com/watch?v=xoIHkM4KpHM