How to handle mouseover event with this textarea resize sign?:

The easiest solution is to check if the cursor is in a small area in the right-bottom corner. But maybe there's another solution?
Since you didn't post what exactly you're trying to do here. Check the link you might get answers
you can add the code that you want to execute when the mouseover event occurs. For example, you could change the cursor to a resize cursor to indicate that the element can be resized:
const resizeSign = document.querySelector('.resize-sign');
resizeSign.addEventListener('mouseover', () => {
document.body.style.cursor = 'resize';
});
resizeSign.addEventListener('mouseout', () => {
document.body.style.cursor = 'default';
});
new ResizeObserver(outputsize).observe(textbox)` – Suhail Qureshi Feb 14 '23 at 19:44