In a React tutorial, how does React know that the number specified as a dimension is in pixels?

https://react.dev/learn#displaying-data

const user = {
  name: 'Hedy Lamarr',
  imageUrl: 'https://i.imgur.com/yXOvdOSs.jpg',
  imageSize: 90,
};

export default function Profile() {
  return (
    <>
      <h1>{user.name}</h1>
      <img
        className="avatar"
        src={user.imageUrl}
        alt={'Photo of ' + user.name}
        style={{
          width: user.imageSize, // Here...
          height: user.imageSize // ...and here.
        }}
      />
    </>
  );
}

How does React know that user.imageSize, which is a number, has the pixels as a unit? How does it know that it is not, for example, % or cm?

>Solution :

when using react jsx css properties unitless values are treated as pixel values. So in your example

style={{
  width: user.imageSize, // Here...
  height: user.imageSize // ...and here.
}}

is explicitly equivalent to

style={{
  width: `${user.imageSize}px`
  height: `${user.imageSize}px`
}}

To use any other units, you just specify the ones you want to use.