I made some tests in angular to display an alert and both worked just fine.
This example:
<a href="" test>Foo</a>
js (outside controller):
myApp.directive('test', function($compile){
return function(scope, element, attrs){
element.bind('click', function(){
alert('Foo');
});
}
});
and this example:
Foo
js (inside controller):
$scope.test = function(){
alert('Foo');
}
Like I said, both worked. But, which one is correct for manipulating DOM and event handlers?
I'd say that you should use directives when you want to make it a component for reuse for example.
That's okay to use ng-click for a simple alert, but imagine when more DOM manipulation is needed. In this case a directive is a better solution.
This is a good read about AngularJS directives: The Hitchhiker’s Guide to the Directive.
Related
How to know when all interpolation and processing on a given page has been completed?
compile: function (tElement, tAttrs) {
return function (scope, element, attrs) {
element.html(tpl);
$compile(element.contents())(scope);
};
},
This is not synchronous. If there are {{stuff}} and ng-repeat="..." etc... they will not all be guaranteed to be completed when the link function returns.
I need a way to know when the page has rendered and there's no more directives to process so that I can then use #hashes to navigate to elements created on the page by angular. (using $anchorScroll)
Maybe try this:
$scope.$on('$viewContentLoaded', function() {
// ....
});
There is a directive in angular for this very specific reason ; ngCloak.
The ngCloak directive is used to prevent the Angular html template
from being briefly displayed by the browser in its raw (uncompiled)
form while your application is loading. Use this directive to avoid
the undesirable flicker effect caused by the html template display.
Doc # https://docs.angularjs.org/api/ng/directive/ngCloak
Similar Question on Quora; How do I hide a div with AngularJS until ng-repeat has finished processing? # https://www.quora.com/How-do-I-hide-a-div-with-AngularJS-until-ng-repeat-has-finished-processing
This is another way to do it, but I prefer to use angular directive.
<li ng-repeat="opt in menuItems" my-custom-repeat-listener> </li>
and then on the directive something sort of like
if(scope.$last) { /*fire event or etc to show the list items*/ }
I really love how the new ng-click directive in Angular now automatically includes functionality for touch events. However, I am wondering if it is possible to access that touch-event service from my custom directive? I have lots of directives that require that I bind a click event to the given element, but I'm simply doing that using the typical jquery syntax (ex: element.on('click', function(){ ... })). Is there a way that I can bind an ng-click event to an element within a directive? Without having to manually put a ng-click tag on my element in the HTML of my view...?
I want to be able to harness the power of both click and touch events. I could obviously import a library (such as HammerJS or QuoJS) but I would prefer not to have to do that, especially since Angular is already doing it.
I can access the $swipe service and bind different elements to that, but is there a similar service for ngTouch?
For reference, this is an example of when I would want to do this:
mod.directive('datepicker', ['$timeout', function($timeout){
return {
link: function(scope, elem, attrs){
var picker = new DatePicker();
elem.on('click', function(e){
picker.show();
});
// I would rather do something like:
// elem.on('ngTouch', function(){ ... });
//
// or even:
// $ngTouch.bind(elem, {'click': ..., 'touch': ...});
}
}
}]);
UPDATE: As noted by below, the source code for the ng-click directive is here. Can anyone see a way to harness that code and turn it into a "bindable" service?
I don't think that's quite the right approach. I'd approach this by using a template within your directive and then using ngTouch within that.
mod.directive('datepicker', ['$timeout', function ($timeout) {
return {
template: '<div ng-touch="doSomethingUseful()"></div>',
link: function (scope, elem, attrs) {
var picker = new DatePicker();
scope.doSomethingUseful = function () {
// Your code.
}
}
}
}]);
UPDATE
Full example with additional attributes on the directive element:
http://codepen.io/ed_conolly/pen/qJDcr
When you create a directive, you can put code into the compiler, the link function or the controller.
In the docs, they explain that:
compile and link function are used in different phases of the angular
cycle
controllers are shared between directives
However, for me it is not clear, which kind of code should go where.
E.g.: Can I create functions in compile and have them attached to the scope in link or only attach functions to the scope in the controller?
How are controllers shared between directives, if each directive can have its own controller? Are the controllers really shared or is it just the scope properties?
Compile :
This is the phase where Angular actually compiles your directive. This compile function is called just once for each references to the given directive. For example, say you are using the ng-repeat directive. ng-repeat will have to look up the element it is attached to, extract the html fragment that it is attached to and create a template function.
If you have used HandleBars, underscore templates or equivalent, its like compiling their templates to extract out a template function. To this template function you pass data and the return value of that function is the html with the data in the right places.
The compilation phase is that step in Angular which returns the template function. This template function in angular is called the linking function.
Linking phase :
The linking phase is where you attach the data ( $scope ) to the linking function and it should return you the linked html. Since the directive also specifies where this html goes or what it changes, it is already good to go. This is the function where you want to make changes to the linked html, i.e the html that already has the data attached to it. In angular if you write code in the linking function its generally the post-link function (by default). It is kind of a callback that gets called after the linking function has linked the data with the template.
Controller :
The controller is a place where you put in some directive specific logic. This logic can go into the linking function as well, but then you would have to put that logic on the scope to make it "shareable". The problem with that is that you would then be corrupting the scope with your directives stuff which is not really something that is expected.
So what is the alternative if two Directives want to talk to each other / co-operate with each other? Ofcourse you could put all that logic into a service and then make both these directives depend on that service but that just brings in one more dependency. The alternative is to provide a Controller for this scope ( usually isolate scope ? ) and then this controller is injected into another directive when that directive "requires" the other one. See tabs and panes on the first page of angularjs.org for an example.
I wanted to add also what the O'Reily AngularJS book by the Google Team has to say:
Controller - Create a controller which publishes an API for communicating across directives. A good example is Directive to Directive Communication
Link - Programmatically modify resulting DOM element instances, add event listeners, and set up data binding.
Compile - Programmatically modify the DOM template for features across copies of a directive, as when used in ng-repeat. Your compile function can also return link functions to modify the resulting element instances.
A directive allows you to extend the HTML vocabulary in a declarative fashion for building web components. The ng-app attribute is a directive, so is ng-controller and all of the ng- prefixed attributes. Directives can be attributes, tags or even class names, comments.
How directives are born (compilation and instantiation)
Compile: We’ll use the compile function to both manipulate the DOM before it’s rendered and return a link function (that will handle the linking for us). This also is the place to put any methods that need to be shared around with all of the instances of this directive.
link: We’ll use the link function to register all listeners on a specific DOM element (that’s cloned from the template) and set up our bindings to the page.
If set in the compile() function they would only have been set once (which is often what you want). If set in the link() function they would be set every time the HTML element is bound to data in the
object.
<div ng-repeat="i in [0,1,2]">
<simple>
<div>Inner content</div>
</simple>
</div>
app.directive("simple", function(){
return {
restrict: "EA",
transclude:true,
template:"<div>{{label}}<div ng-transclude></div></div>",
compile: function(element, attributes){
return {
pre: function(scope, element, attributes, controller, transcludeFn){
},
post: function(scope, element, attributes, controller, transcludeFn){
}
}
},
controller: function($scope){
}
};
});
Compile function returns the pre and post link function. In the pre link function we have the instance template and also the scope from the controller, but yet the template is not bound to scope and still don't have transcluded content.
Post link function is where post link is the last function to execute. Now the transclusion is complete, the template is linked to a scope, and the view will update with data bound values after the next digest cycle. The link option is just a shortcut to setting up a post-link function.
controller: The directive controller can be passed to another directive linking/compiling phase. It can be injected into other directices as a mean to use in inter-directive communication.
You have to specify the name of the directive to be required – It should be bound to same element or its parent. The name can be prefixed with:
? – Will not raise any error if a mentioned directive does not exist.
^ – Will look for the directive on parent elements, if not available on the same element.
Use square bracket [‘directive1′, ‘directive2′, ‘directive3′] to require multiple directives controller.
var app = angular.module('app', []);
app.controller('MainCtrl', function($scope, $element) {
});
app.directive('parentDirective', function() {
return {
restrict: 'E',
template: '<child-directive></child-directive>',
controller: function($scope, $element){
this.variable = "Hi Vinothbabu"
}
}
});
app.directive('childDirective', function() {
return {
restrict: 'E',
template: '<h1>I am child</h1>',
replace: true,
require: '^parentDirective',
link: function($scope, $element, attr, parentDirectCtrl){
//you now have access to parentDirectCtrl.variable
}
}
});
Also, a good reason to use a controller vs. link function (since they both have access to the scope, element, and attrs) is because you can pass in any available service or dependency into a controller (and in any order), whereas you cannot do that with the link function. Notice the different signatures:
controller: function($scope, $exceptionHandler, $attr, $element, $parse, $myOtherService, someCrazyDependency) {...
vs.
link: function(scope, element, attrs) {... //no services allowed
this is a good sample for understand directive phases
http://codepen.io/anon/pen/oXMdBQ?editors=101
var app = angular.module('myapp', [])
app.directive('slngStylePrelink', function() {
return {
scope: {
drctvName: '#'
},
controller: function($scope) {
console.log('controller for ', $scope.drctvName);
},
compile: function(element, attr) {
console.log("compile for ", attr.name)
return {
post: function($scope, element, attr) {
console.log('post link for ', attr.name)
},
pre: function($scope, element, attr) {
$scope.element = element;
console.log('pre link for ', attr.name)
// from angular.js 1.4.1
function ngStyleWatchAction(newStyles, oldStyles) {
if (oldStyles && (newStyles !== oldStyles)) {
forEach(oldStyles, function(val, style) {
element.css(style, '');
});
}
if (newStyles) element.css(newStyles);
}
$scope.$watch(attr.slngStylePrelink, ngStyleWatchAction, true);
// Run immediately, because the watcher's first run is async
ngStyleWatchAction($scope.$eval(attr.slngStylePrelink));
}
};
}
};
});
html
<body ng-app="myapp">
<div slng-style-prelink="{height:'500px'}" drctv-name='parent' style="border:1px solid" name="parent">
<div slng-style-prelink="{height:'50%'}" drctv-name='child' style="border:1px solid red" name='child'>
</div>
</div>
</body>
compile: used when we need to modify directive template, like add new expression, append another directive inside this directive
controller: used when we need to share/reuse $scope data
link: it is a function which used when we need to attach event handler or to manipulate DOM.
In the link function, is there a more "Angular" way to bind a function to a click event?
Right now, I'm doing...
myApp.directive('clickme', function() {
return function(scope, element, attrs) {
scope.clickingCallback = function() {alert('clicked!')};
element.bind('click', scope.clickingCallback);
} });
Is this the Angular way of doing it or is it an ugly hack? Perhaps I shouldn't be so concerned, but I'm new to this framework and would like to know the "correct" way of doing things, especially as the framework moves forward.
You may use a controller in directive:
angular.module('app', [])
.directive('appClick', function(){
return {
restrict: 'A',
scope: true,
template: '<button ng-click="click()">Click me</button> Clicked {{clicked}} times',
controller: function($scope, $element){
$scope.clicked = 0;
$scope.click = function(){
$scope.clicked++
}
}
}
});
Demo on plunkr
More about directives in Angular guide. And very helpfull for me was videos from official Angular blog post About those directives.
I think it is fine because I've seen many people doing this way.
If you are just defining the event handler within the directive,
you do not have to define it on the scope, though.
Following would be fine.
myApp.directive('clickme', function() {
return function(scope, element, attrs) {
var clickingCallback = function() {
alert('clicked!')
};
element.bind('click', clickingCallback);
}
});
Shouldn't it simply be:
<button ng-click="clickingCallback()">Click me<button>
Why do you want to write a new directive just to map your click event to a callback on your scope ? ng-click already does that for you.
You should use the controller in the directive and ng-click in the template html, as suggested previous responses. However, if you need to do DOM manipulation upon the event(click), such as on click of the button, you want to change the color of the button or so, then use the Link function and use the element to manipulate the dom.
If all you want to do is show some value on an HTML element or any such non-dom manipulative task, then you may not need a directive, and can directly use the controller.
In this case, no need for a directive. This does the job :
<button ng-click="count = count + 1" ng-init="count=0">
Increment
</button>
<span>
count: {{count}}
</span>
Source: https://docs.angularjs.org/api/ng/directive/ngClick
myApp.directive("clickme",function(){
return function(scope,element,attrs){
element.bind("mousedown",function(){
<<call the Controller function>>
scope.loadEditfrm(attrs.edtbtn);
});
};
});
this will act as onclick events on the attribute clickme
I wrote this simple jsfiddle in which I do (successfully) some basic addClass on a directive in a ng-repeat.
http://jsfiddle.net/rv6u2/5/
Now, my question is: which is the best (or intended) place to do such DOM manipulations:
A. In the directive?
B. In the controller?
Both possibilities are shown in my example.
Code:
var TestApp = angular.module("TestApp", ['ngResource']);
TestApp.directive('onLoad', function() {
return {
restrict: 'A',
link: function(scope, elm, attrs) {
elm.addClass('loaded'); // A: DOM manipulation in directive
scope.initMe(scope.$eval(attrs.onLoad2), elm); // B: DOM manipulation handled in controller
}
};
});
thanks in advance :)
NEVER manipulate the dom inside of controllers.
Controllers should just use services and update attributes of $scope. All DOM manipulation should be made by directives and(in some cases) services(e.g. $anchorScroll)
See the concepts of angularjs here
UPDATE: Example of the correct way here
A more "Angular way" of setting class loaded2 would be as follows (which avoids DOM manipulation inside the controller):
In the HTML, declare a model for the class (myClass):
<div ng-repeat="item in items" ng-model="item" on-load="initMe(item)" ng-class="myClass">
In the link function, just call the controller method:
scope.initMe()
In the controller, manipulate the model/$scope property:
$scope.initMe = function() {
$scope.myClass = "loaded2";
}
Changing the model/scope will automatically update the view.
This method is useful if you want to declare in the HTML that a class is being controlled by $scope property myClass. However, using elm.addClass() inside the linking function is more self-contained and easier to maintain (and I like that approach better).