Function $watchCollectionInterceptor

lib/test/angular/1.4.3/angular.js:15465–15543

(_value)

        var oldLength = 0;

        function $watchCollectionInterceptor(_value) {
          newValue = _value;
          var newLength, key, bothNaN, newItem, oldItem;

          // If the new value is undefined, then return undefined as the watch may be a one-time watch
          if (isUndefined(newValue)) return;

          if (!isObject(newValue)) { // if primitive
            if (oldValue !== newValue) {
              oldValue = newValue;
              changeDetected++;
            }
          } else if (isArrayLike(newValue)) {
            if (oldValue !== internalArray) {
              // we are transitioning from something which was not an array into array.
              oldValue = internalArray;
              oldLength = oldValue.length = 0;
              changeDetected++;
            }

            newLength = newValue.length;

            if (oldLength !== newLength) {
              // if lengths do not match we need to trigger change notification
              changeDetected++;
              oldValue.length = oldLength = newLength;
            }
            // copy the items to oldValue and look for changes.
            for (var i = 0; i < newLength; i++) {
              oldItem = oldValue[i];
              newItem = newValue[i];

              bothNaN = (oldItem !== oldItem) && (newItem !== newItem);
              if (!bothNaN && (oldItem !== newItem)) {
                changeDetected++;
                oldValue[i] = newItem;
              }
            }
          } else {
            if (oldValue !== internalObject) {
              // we are transitioning from something which was not an object into object.
              oldValue = internalObject = {};
              oldLength = 0;
              changeDetected++;
            }
            // copy the items to oldValue and look for changes.
            newLength = 0;
            for (key in newValue) {
              if (newValue.hasOwnProperty(key)) {
                newLength++;
                newItem = newValue[key];
                oldItem = oldValue[key];

                if (key in oldValue) {
                  bothNaN = (oldItem !== oldItem) && (newItem !== newItem);
                  if (!bothNaN && (oldItem !== newItem)) {
                    changeDetected++;
                    oldValue[key] = newItem;