[javascript] Javascript: How to remove the last character from a div or a string?

I have a div with a string of content in it. The content is not stored in a variable and I would like to remove the last character of the text in this div. Any help please?

More info:

I have a text field, and upon entering text into the text field, the text appears in a div in large writing. When the user hits the back-space key, I want the last character in the div to be deleted. I am mainly using jQuery to achieve this. Here is my code:

$(document).ready(function(){
    $("#theInput").focus();   //theInput is the text field

    $('#theInput').on('keypress', printKeyPress);

    function printKeyPress(event)
    {
        //#mainn is the div to  hold the text
        $('#mainn').append(String.fromCharCode(event.keyCode));
        if(event.keyCode ==8)   //if backspace key, do below
        {
            $('#mainn').empty();  //my issue is located here...I think
        }
    }

});

I have attempted $('#mainn').text.slice(0,-1);

I have also tried storing the value of #theInput in a variable and then printing it, but that didn't work. Any ideas ?

Are u sure u want to remove only last character. What if the user press backspace from the middle of the word.. Its better to get the value from the field and replace the divs html. On keyup

$("#div").html($("#input").val());

var string = "Hello";
var str = string.substring(0, string.length-1);
alert(str);

http://jsfiddle.net/d72ML/