How to access the data from data* attribute using JavaScript?

Scenario: When the user clicks on it, the data should be passed into someFunction().

<span id="someid" onClick={() => someFunction()} data-video-page="some data" class="dot" />`

I tried using getAttributes(), querySelector() methods until now to get the data from data attributes. But one of them are working, in fact they are returning none.

There is a React.js tag in your question, so I'll assume that this is for using data-set in React.js.

For React.js, this is how data-set can be used if you want to pass the data to some function on a click event. You can also visit the live demo here: stackblitz

const handleClick = (event) => {

  // Your data is stored in event.currentTarget.dataset
  // Here we get the data by destructuring it
  // The name video-page need to change to videoPage for JS rules

  const { videoPage } = event.currentTarget.dataset;
  console.log(videoPage);

  // Result printed: "your data"
  // You can also run someFunction(videoPage) here
};

export default function App() {
  return (
    <button data-video-page="your data" onClick={handleClick}>
      TEST
    </button>
  );
}