Why doesn't js DOM work in react?

Question

JavaScript

Good day, tell me why it is impossible to pick up all classes from the list elements through js DOM? And how to highlight clicked element in react? Only through ref ?

class MyComponent extends Component {
  click=(e)=>{
     document.getElementsByTagName('li').classList.remove("active")

    e.target.className = "active"
  }

  render() {
      return (
          <ul>
              <li onClick={(e)=>this.click(e)}>item1</li>
              <li onClick={(e)=>this.click(e)}>item2</li>
              <li onClick={(e)=>this.click(e)}>item3</li>
          </ul>
      )
  }
}

Answer 1

Such things are done in react not directly through work with the house, but through work with the internal state of the component. Read the documentation, take a training course about tic-tac-toe.