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ViewsHow exactly is React's Virtual DOM faster?
I understand that there are two arguments for React's Virtual DOM being faster -
It updates ONLY those elements that actually need to be updated (using diff).
It batches the updates and hence we update the real DOM only a single time. Thus the repainting is also done only once which otherwise would have been done multiple times.
I have questions regarding both these points -
As far as I know, all the modern browsers are efficient enough to update only the required elements in the DOM. For example, if I have two 'p' tags and I change the text in one of the p tags using a button click, then only that p tag will be updated by safari (I have verified this using paint flashing). So how is point 1 an advantage if it is already being implemented by the browsers?
How exactly does React batch the updates? Eventually React will also have to use the DOM api to update the real DOM. So why is that if we directly use the DOM api then the changes will not be batched whereas when React uses it then they are batched?
1 answers
Answer question0
Once React knows which virtual DOM objects have changed, then React updates only those objects, in the real DOM. This makes the performance far better when compared to manipulating the real DOM directly. This makes React standout as a high performance JavaScript library.
Regarding the Batch Update:
React follows a batch update mechanism to update the real DOM. Hence, leading to increased performance. This means that updates to the real DOM are sent in batches, instead of sending updates for every single change in state.
The repainting of the UI is the most expensive part, and React efficiently ensures that the real DOM receives only batched updates to repaint the UI.