What type of data does the virtual DOM in JavaScript represent?

The virtual DOM in JavaScript is not a special, dedicated data type. It is more of a concept and its implementation using regular JavaScript objects.

These objects represent a lightweight, in-memory representation of the real DOM tree. Each such object describes a DOM node with its:

• Type (for example, 'div', 'span', 'p')
• Attributes ({ id: 'myElement', class: 'active' })
• Child elements (an array of other virtual DOM objects)

When the application's state changes, a new virtual DOM tree is created. Then this new tree is compared (diffing) with the previous virtual tree, and the minimal set of changes needed to be applied to the real DOM is determined. This process is called patching.

// Example of a simple virtual DOM node
const virtualNode = {
  type: 'div',
  props: {
    id: 'container',
    className: 'wrapper'
  },
  children: [
    {
      type: 'h1',
      props: {},
      children: ['Hello, World!'] // Text node represented by a string
    },
    {
      type: 'button',
      props: {
        onClick: () => console.log('Clicked!')
      },
      children: ['Click me']
    }
  ]
};