title: How to check type of value inserted in HTML table using JavaScript
body: <p>I am working on a contenteditable HTML table. I have to assure that only numeric values can be inserted, and show an alert when user tries to insert strings, or something that is not a number. How can I do this? I've searched online but I did not find anything yet.</p>
  
  <p>btw, I use prompts to communicate: is there a way to deny the user to check the option "don't let the browser keep prompting things"?</p>