javascript - $watch JSON 中的对象 Angularjs

Question

我想在指令中为 json 对象的特定部分创建一个 $watch，但它似乎不接受语法(没有出现错误，但它永远不会进入 watch )

link: function (scope, element) {
scope.JsonObject={
    profs:{
        prof1:[{
           name:example1a,
           id:example1b
        }],
        prof2:[{
           name:example2a,
           id:example2b
        }]
     }
 }  

scope.teachers=scope.JsonObject['profs']

//until here all ok

for ( var  teacher in scope.teachers){
    //stuff to do
    console.log("creating watch of " + teacher);

    scope.$watch('teachers[teacher]', function() {  //here seems to be the problem (it doesnt seem to accept JsonObject.teacher)       
    //stuff to do

}, true);
}

Answer 1

以前，teachers[teacher] 是 undefined 因为没有 ' '(引号)围绕老师。

for (var teacher in $scope.teachers){
    $scope.$watch("teachers['"+ teacher +"']", function(newValue, oldValue) {
      alert("changed");
   }, true);
}