ReactJs or react.js is a JavaScript library created by Facebook for the creation of user interfaces. These interfaces are intended to be reused as often as possible. reactjs is based on the Virtual Dom concept.
Virtual Dom is the revolution that has made ReactJs so successful. The normal DOM is a document, sentence or style represented by a web browser page.
Its structure is then represented as a node with a tree-like appearance. The virtual DOM, on the other hand, is a more advanced representation of this DOM, written in JavaScript.
Instead of generating a normal web page with the various aspects, a virtual DOM representing the aspect of the next web page to be displayed is instead created in memory in conjunction with the displayed DOM.
In the event of a modification, the virtual DOM compares the web page displayed with the one requested. In the end, it will only modify the part of the virtual DOM that requires modification.
It is therefore the final rendering of this virtual DOM that will be displayed to the user calling up the web page.
Obviously, as the virtual Dom is in JavaScript, it's much easier to manipulate than the DOM we've always known. So you can easily make dozens of modifications in a matter of seconds.
Which is a real plus when it comes to interacting intuitively with the user. No wonder Facebook has so many users today. Not least thanks to its reactjs-optimized News Feed.
In other words, if you want to offer a user-oriented interface, reactjs, with its new notion of virtual Dom, should be a real companion to help you create your successful application.
And if you trust the right web developer, he'll be able to suggest or advise you on how to use it, and even put it to good use.