How to add a timer on page load that stops when button is clicked?

I want to add a timer to the page where it starts on page load.

Where it goes up in milliseconds.

Then stops when the mouse is clicked on the button.

How would I create a code example of that?

That is all I am trying to do in the code.

Add a timer that starts on page load.

Goes up in milliseconds.

Then stops when the button is clicked.

https://jsfiddle.net/xvkwmndq/

I was able to do this, but how am I able to see the numbers on the screen?

// Counter
var enterDate = new Date();
function secondsSinceEnter()
{
  return (new Date() - enterDate) / 1000;
}

// Usage example
document.querySelector('button').onclick = function() {
  var sec = secondsSinceEnter();
  if (sec < 10)
      this.innerText = sec + " seconds";
  else
      this.innerText = 'You are here like for eternity';
};

Have you tried with window.onload?
window.onload

or useEffect in React…

You would want to call setInterval when page loads then in the setInterval have a function that updates the text do the time

In your button you can clearInterval to stop