JavaScript - Prevent "CTRL" and "ALT" being used for special characters

Question

1. With the code below, is there anyway of preventing the user from entering special characters that are generated by pressing CTRL + ALT + 4 for example?
2. That produces the euro currency sign. All the below code works perfectly, I just need to prevent any special characters that are generated from CTRL + ALT
3. Prevent the user from using their mouse to right click and paste the content in
4. Working with IE8

`

$("#txtboxToFilter").keydown(function (e) {
        // Allow: backspace, delete, tab, escape, enter and .
    if ($.inArray(e.keyCode, [46, 8, 9, 27, 13, 110, 190]) !== -1 ||
         // Allow: Ctrl+A
        (e.keyCode == 65 && e.ctrlKey === true) ||
         // Allow: Ctrl+C
        (e.keyCode == 67 && e.ctrlKey === true) ||
         // Allow: Ctrl+X
        (e.keyCode == 88 && e.ctrlKey === true) ||
         // Allow: home, end, left, right
        (e.keyCode >= 35 && e.keyCode <= 39)) {
             // let it happen, don't do anything
             return;
    }
    // Ensure that it is a number and stop the keypress
    if ((e.shiftKey || (e.keyCode < 48 || e.keyCode > 57)) && (e.keyCode < 96 || e.keyCode > 105)) {
        e.preventDefault();
    }
});`

Answer 1

If you want to allow only certain keyboard shorcuts, you can disable anything but whatever you let pass. You can also decide to list everything that you want disabled, and allow everything else to execute. A simple way I see this can go is to disable the Ctrl key and the Alt key if they are pressed simultaneously, as such:

$("#txtboxToFilter").keydown(function (e) {
    if (e.ctrlKey === true && e.altKey === true) {
         return;
    }
    else {
        //Do whatever;
        if (e.key === "Tab") {
            //Tab was pressed
        }
        else if (e.key === "H") {
           //Shift H was pressed
        }
        else if (["Home", "End", "PageUp", "PageDown"].includes(e.key) === true) {
            //Navigational Keys Were Pressed
        }
        else if (["ArrowUp", "ArrowDown", "ArrowRight", "ArrowLeft"].includes(e.key) === true) {
            //Directional Arrows Were Pressed
        }
    }
 });

And may I recommend that you use e.key instead of e.keyCode, e.which, or code, because it is more supported, and it is way easier to understand. Just take a look at the code snippet above, there are examples of e.key. Besides, there is no confusion with numbers, because the key names are used. If you wanted to use the Windows Key on Windows, the Search key on Chromebooks, e.key === "Meta" is the way to go.

Hope this extra information helps!!!