How to change alert function into ancher tag in javascript When the user click on the button the login page will appear alert never show [closed]

echo "<script> function a(){alert('⚠️ Login is required to add this product into cart');}</script>";

source https://stackoverflow.com/questions/73653703/how-to-change-alert-function-into-ancher-tag-in-javascript-when-the-user-click-o