What does Angular 2 use to update the DOM. Is it Shadow DOM or Virtual DOM ? Was there any such concept in Angular 1?
React and Vue are using Virtual DOM and Angular use direct DOM rendering system.
It's the same thing that Angular did with version 1.x, but it is optimized and there is a surprise for you :)
It is much faster to work with JavaScript objects than with DOM, because nothing drown on screen
update
Shadow DOM is now directly supported.
original
Angular2 doesn't use shadow DOM (default) nor virtual DOM.
With encapsulation: ViewEncapsulation.Emulated
(default) there is no shadow DOM because style encapsulation is only emulated.
encapsulation: ViewEncapsulation.Native
enables shadow DOM on browsers that support it natively or it's again emulated when the webcomponents polyfill is loaded.
Shadow DOM is also not targeting performance as virtual DOM is, but style encapsulation.
Angular2 doesn't use virtual DOM at all.
Angular2 has change detection that detects changes to the model and only updates the parts of the DOM that need to be changed according to the model changes.
For more details see also Is Shadow DOM fast like Virtual DOM in React.js?