How to obtain keycode in VB

The following Code Only the right-click shielding, CTRL + N, Shift + F10, F5 refresh, and backspace keys are implemented.
Function keydown (){
// Shield right-click, CTRL + N, Shift + F10, F5 refresh, and backspace key
// Alert ("ASCII Code:" + event. keycode );
If (window. event. altkey )&&
(Window. event. keycode = 37) | // mask Alt + direction key seek
(Window. event. keycode = 39) {// mask Alt + direction key →
Alert ("You are not allowed to use Alt + arrow keys to move forward or backward the webpage! ");
Event. returnvalue = false;
}
If (event. keycode = 8) | // shield the unregeed deletion key
(Event. keycode = 116) | // block the F5 refresh key
(Event. keycode = 112) | // block the F1 refresh key
(Event. ctrlkey & event. keycode = 82) {// Ctrl + R
Event. keycode = 0;
Event. returnvalue = false;
}
If (event. ctrlkey) & (event. keycode = 78) // block Ctrl + n
Event. returnvalue = false;
If (event. shiftkey) & (event. keycode = 121) // block SHIFT + F10
Event. returnvalue = false;
If (window. event. srcelement. tagname = "A" & window. event. shiftkey)
Window. event. returnvalue = false; // block shift with the left mouse button to open a new page
If (window. event. altkey) & (window. event. keycode = 115) {// block Alt + F4
Window. showmodelessdialog ("about: blank", "", "dialogwidth: 1px; dialogheight: 1px ");
Return false ;}
}