How can I make a backspace button for my calculator?

Question

I'm making a simple calculator. I've made almost everything of the calculator. But I can't make a backspace button for my calculator. :(
If anyone know any easy way then please tell... :)

I made my reset button like this:

function reset() {
document.getElementById('display').value="";
}

But I have no idea to make a backspace button.

Answer 1

function backspace(){
var len=document.getElementById('display');
var inner=len.innerHTML;
len="";
inner=inner.split("");
inner=inner.splice(inner.length-1,1)
inner=inner.join("");
len.value=inner;
}

Answer 2

since the value of your calculator is being stored as a string remove the last value in the string