Getting Started with Events - Consume and Dispatch

Question

I am working on a Javascript file that will catch and consume a User's keystroke, when a specific one is pressed. Instead, that keystroke should dispatch a sequence of keystrokes.

So far, I have been able to successfully catch and consume the user's keystroke. However, I have not yet been able to dispatch the corresponding sequence.

The goal: When a user pressed [ctrl + m], it should instead execute [ctrl + i] [ctrl+o] [ctrl+m] (no recursion)

The broken code:

function replaceKeyEvent(evtobj) {

if(evtobj.keyCode == 73 && evtobj.ctrlKey){
 window.alert("101");   
 }
if (evtobj.keyCode == 77 && evtobj.ctrlKey) {

  evtobj.preventDefault();
   window.alert("test");
/*
 var evt = document.createEvent("KeyboardEvent");
 evt.initKeyboardEvent();
 evt.ctrlKey = true;
 */
var e = new KeyboardEvent("keypress", {
    bubbles : true,
    cancelable : true,
    char : "I",
    key : "i",
    shiftKey : false,
    ctrlKey : true,
    keyCode : 73

 });
 document.dispatchEvent(e);
 window.alert(e);

}
}

document.onkeydown = replaceKeyEvent;

so far I am just trying to catch the [ctrl + m] and send the first keyboardevent (which is ctrl+i), and as a test, when the script sees the ctrl+i it should alert 101 (intro joke yes I know).

Please let me know if anyone can assist. I am very new to dispatching events in general, let alone Javascript

Edit: also any notes on cross functionality between environments (browser, os, etc.,) please point me in the right direction
edit2: updated code, still not working, stopping for the night