Allow only Numeric values in ASP Text box control using JavaScript

This allows only numeric (either whole or decimal) values in ASP Textbox control using JavaScript using ASP textbox key down event to fire the JavaScript function.

Example

<asp:TextBox ID="txtDaysOutLB" Text="" MaxLength="4" onkeydown="return jsDecimals(event);" Width="75px" runat="server"></asp:TextBox>

Javascript Function

function jsDecimals(e) {

    var evt = (e) ? e : window.event;
    var key = (evt.keyCode) ? evt.keyCode : evt.which;
    if (key != null) {
        key = parseInt(key, 10);
        if ((key < 48 || key > 57) && (key < 96 || key > 105)) {
            if (!jsIsUserFriendlyChar(key, "Decimals")) {
                return false;
            }
        }
        else {
            if (evt.shiftKey) {
                return false;
            }
        }
    }
    return true;
}

// Function to check for user friendly keys  
//------------------------------------------
function jsIsUserFriendlyChar(val, step) {
    // Backspace, Tab, Enter, Insert, and Delete  
    if (val == 8 || val == 9 || val == 13 || val == 45 || val == 46) {
        return true;
    }
    // Ctrl, Alt, CapsLock, Home, End, and Arrows  
    if ((val > 16 && val < 21) || (val > 34 && val < 41)) {
        return true;
    }
    if (step == "Decimals") {
        if (val == 190 || val == 110) {  //Check dot key code should be allowed
            return true;
        }
    }
    // The rest  
    return false;
}