Function $watchCollectionAction

test/angular/1.6/angular.js:18400–18427

()

        }

        function $watchCollectionAction() {
          if (initRun) {
            initRun = false;
            listener(newValue, newValue, self);
          } else {
            listener(newValue, veryOldValue, self);
          }

          // make a copy for the next time a collection is changed
          if (trackVeryOldValue) {
            if (!isObject(newValue)) {
              //primitive
              veryOldValue = newValue;
            } else if (isArrayLike(newValue)) {
              veryOldValue = new Array(newValue.length);
              for (var i = 0; i < newValue.length; i++) {
                veryOldValue[i] = newValue[i];
              }
            } else { // if object
              veryOldValue = {};
              for (var key in newValue) {
                if (hasOwnProperty.call(newValue, key)) {
                  veryOldValue[key] = newValue[key];
                }
              }
            }
          }
        }

        return this.$watch(changeDetector, $watchCollectionAction);
      },