demo/bundle.js
/**
             * Attempt to create an observer instance for a value,
             * returns the new observer if successfully observed,
             * or the existing observer if the value already has one.
             */
Attempt to create an observer instance for a value,
returns the new observer if successfully observed,
or the existing observer if the value already has one.
Attempt to create an observer instance for a value returns the new observer if successfully observed or the existing observer if the value already has one .
function observe (value, asRootData) {
              if (!isObject(value) || value instanceof VNode) {
                return
              }
              var ob;
              if (hasOwn(value, '__ob__') && value.__ob__ instanceof Observer) {
                ob = value.__ob__;
              } else if (
                shouldObserve &&
                !isServerRendering() &&
                (Array.isArray(value) || isPlainObject(value)) &&
                Object.isExtensible(value) &&
                !value._isVue
              ) {
                ob = new Observer(value);
              }
              if (asRootData && ob) {
                ob.vmCount++;
              }
              return ob
            }
function observe ( value , asRootData ) { if ( ! isObject ( value ) || value instanceof VNode ) { return } var ob ; if ( hasOwn ( value , '__ob__' ) && value . __ob__ instanceof Observer ) { ob = value . __ob__ ; } else if ( shouldObserve && ! isServerRendering ( ) && ( Array . isArray ( value ) || isPlainObject ( value ) ) && Object . isExtensible ( value ) && ! value . _isVue ) { ob = new Observer ( value ) ; } if ( asRootData && ob ) { ob . vmCount ++ ; } return ob }
Attempt to create an observer instance for a value,
 returns the new observer if successfully observed,
 or the existing observer if the value already has one.
Attempt to create an observer instance for a value returns the new observer if successfully observed or the existing observer if the value already has one .