document.getElementById().value doesn't set the value

Your response is almost certainly a string. You need to make sure it gets converted to a number:

document.getElementById("points").value= new Number(request.responseText);

You might take a closer look at your responseText. It sound like you are getting a string that contains quotes. If you are getting JSON data via AJAX, you might have more consistent results running it through JSON.parse().

document.getElementById("points").value= new Number(JSON.parse(request.responseText));

According to my tests with Chrome:

If you set a number input to a Number, then it works fine.

If you set a number input to a String that contains nothing but a number, then it works fine.

If you set a number input to a String that contains a number and some whitespace, then it blanks the input.

You probably have a space or a new line after the data in the server response that you actually care about.

Use document.getElementById("points").value = parseInt(request.responseText, 10); instead.