How do I get the x and y positions of an element in an AngularJS directive
Within the link function part of a directive we have access to the element object. I wish to determine if the element object is within the current viewport / if it is available.
I currently have the following:
link: function (scope, element, attrs, controller) {
var page = angular.element(window);
page.bind('scroll', function () {
var windowScroll = page[0].pageYOffset,
windowHeight = page[0].innerHeight;
// elementScroll = element.xpos; - this is undefined?
// elementScroll = element.getBoundingClientRect().top - this does not work... undefined?
// elementScroll = element[0].getBoundingClientRect().top - this does not work... undefined?
// ... logic follows that if elementScroll is between windowScroll & windowScroll + windowHeight it is visible!
});
I just can't seem to get the x and y positions for my specific element (the directive may be repeated many times).
Please note that I do not intend to install or use jQuery in my application.
You can use element[0].getBoundingClientRect , it works - there is an example:
http://plnkr.co/edit/2eOw3B0MaM2vw3bQuFnf
If you need to track element visibility in angular directive, except scroll you also need to handle events: DOMContentLoaded , load and resize . Also it would be better to create only one handler for those events, and stop tracking element when directive is destroyed
app.directive('trackVisibility', function(){
function isVisible(el) {
var rect = el.getBoundingClientRect();
var clw = (window.innerWidth || document.documentElement.clientWidth);
var clh = (window.innerHeight || document.documentElement.clientHeight) ;
// checks if element is fully visible
//return (rect.top >= 0 && rect.bottom <= clh) && (rect.left >= 0 && rect.right <= clw);
// checks if part of element is visible
return (rect.left <= clw && 0 <= rect.right && rect.top <= clh && 0 <= rect.bottom);
}
var reg = [];
function register(element, fn) {
reg.push([element, fn]);
}
function deregister(element) {
reg = angular.filter(reg, function (item) {
return item[0] !== element;
});
}
angular.element(window).on('DOMContentLoaded load resize scroll', function () {
angular.forEach(reg, function (item) {
item[1](isVisible(item[0]));
});
});
return {
restrict: 'A',
link: function (scope, element, attrs, controller) {
register(element[0], function(isVisible){
scope.$apply(function(){
scope.isVisible = isVisible;
})
});
scope.$on('$destroy', function(){
deregister(element);
})
}
};
});
there is an example: http://plnkr.co/edit/VkCgBvGnCWZ0JCM8tlaJ
I have used this approach to dynamically load images when they become visible.
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