When do we know the actual width of an element in Angular? - angularjs

Question

I'm tring to create a directive that will center a div.
So far, I have this code:
app.directive("setcenter", function () {
return {
scope:{
setcenter: '='
},
link: function (scope, element, attrs) {
scope.$watch('setcenter', function (newValue) {
if (newValue == true) {
var width = element.width();
element.css('position', 'absolute');
element.css('top', '80px');
element.css('left', '50%');
element.css('z-index', '200');
element.css('margin-left', '-' + width / 2 + 'px');
}
});
}
}
});
The problem is the width of the element. The whole point for this directive is that the div that uses this directive, don't have a width set. I want this directive to figure out the width and center the div.
The problem I encounter is that when the directive is invoked, the actual width of the div is not yet known. When I use this in my situation, the div is 800px, but when the page is finished loading, the div is 221px.
So, what can I do to wait till the actual width is known of the div?

Answer 1

First, I only have used this logic when I defined a controller for a directive rather than a link function. So defining it in a link function instead may cause different behavior, but I suggest you try it there first and if you can't get it to work then switch to using a controller.
As far as I can tell, the only change you would need to make this work would be to change $scope to scope calls and $element to element since the dependency injected objects become standard link function parameters.
$scope.getElementDimensions = function () {
return { 'h': $element.height(), 'w': $element.width() };
};
$scope.$watch($scope.getElementDimensions, function (newValue, oldValue) {
//<<perform your logic here using newValue.w and set your variables on the scope>>
}, true);
$element.bind('resize', function () {
$scope.$apply();
});
The idea for this usage came to me after reading a very similar type of usage about watching the $window rather than the current element, the original work can be found here.
Angular.js: set element height on page load

Answer 2

James' answer led me to:
app.directive('measureInto', function () {
return {
restrict: 'A',
link: function (scope, element, attrs) {
scope.$watch(function() {
return element[0].clientWidth;
}, function(value){
scope[attrs.measureInto] = element[0].clientWidth + 10;
});
}
};
});
So, at runtime, I add this and assign into whatever scope variable I want the width of the element I'm looking for

Answer 3

I had a similar issue and found that the dimensions were reliably correct when all the ng-ifs (or anything else using ngAnimate) on the page had been resolved - it's possible something similar is happening here. If so, this would do the trick without adding any new listeners:
$scope.tryGetElementDimensions = function () {
if (!angular.element("your-element") || ((angular.element("your-element")[0].classList).contains("ng-animate")
$timeout(function() {
$scope.tryGetElementDimensions()
})
}
else {
$scope.getElementDimensions()
}
$scope.getElementDimensions = function (){
//whatever you actually wanted to do
}
link: function (scope, element, attrs) {
$scope.tryGetElementDimensions()
}
Angular adds ng-animate and ng-enter, ng-leave classes while it's animating and you can be confident it's finished when these classes have all been removed. $timeout without a second argument just waits for the next digest.

Answer 4

Can't comment yet, therefore this answer.
Found a similar solution like the one strom2357 is suggesting. $timeout works really well to let you know when the dom is ready, and it is super simple. I am using this solution to get the ui-view element width. Found it in a fiddle.
var app = angular.module('app', []);
app.controller('MyController', function($timeout, $scope){
$timeout(function(){
//This is where you would get width or height of an element
alert('DOM ready');
});
alert('DOM not ready');
});