AngularJS How to watch offset top position of elements? -

how watch offset top position (of each element) , if distance top screen border lower 100 px, need hide div. (each div can move on page). please write angular directive.

i can't watch each element top offset.

var app = angular.module('app', []);    app.app.directive('blah', function() {    return {      restrict: 'a',      link: function(scope, element) {        element.show();        scope.$watch(function() {          return element.offset().top > 120        }, function(outofborder) {          if (outofborder) {            element.hide()            console.log(outofborder)          } else {            element.show()            console.log(outofborder)          }        });      }    }  });

.all {  height: 100px;  width: 300px;   border:1px solid;      overflow: scroll;  }  .elements {  height: 30px;  width: 300px;   border:1px solid red;  float: left;    clear: both;  }

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>    <div class="all" ng-app="app">  <div class="elements" blah></div>  <div class="elements" blah></div>  <div class="elements" blah></div>  <div class="elements" blah></div>  <div class="elements" blah></div>  <div class="elements" blah></div>  <div class="elements" blah></div>  <div class="elements" blah></div>  </div>

you add watcher function (not tested + need renaming):

angular.module('blah').directive('blah', function() {   return {     restrict: 'a',     link: function(scope, element) {       scope.$watch(function() {         return element.offset().top < 100       }, function(outofborder) {         if (outofborder) {           element.hide()         } else {           element.show()         }       });     }   } }); 

the reason why code not working value passed $watch evaluated before $watch executed. result, watch top offset on element @ time link executed - constant number.

edit:

if elements not absolutely positioned, calling hide cause remaining elements move make elements hidden. in case use element.addclass('invisible') , element.removeclass('invisible') instead of hiding , showing , define css class as:

.invisible { visibility: hidden; } 

changed visibility not affect other element position.