How can I add a JavaScript keyboard shortcut to an existing JavaScript Function?

An event handler for the document's keyup event seems like an appropriate solution.

Note: KeyboardEvent.keyCode was deprecated in favor of key.

// define a handlerfunction doc_keyUp(e) {    // this would test for whichever key is 40 (down arrow) and the ctrl key at the same time    if (e.ctrlKey && e.key === 'ArrowDown') {        // call your function to do the thing        pauseSound();    }}// register the handler document.addEventListener('keyup', doc_keyUp, false);

If you are only searching for trigger an event after pressing a key, try this:

In this example press 'ALT + a'

document.onkeyup=function(e){  var e = e || window.event; // for IE to cover IEs window event-object  if(e.altKey && e.which == 65) {    alert('Keyboard shortcut working!');    return false;  }}

Here is a fiddle: https://jsfiddle.net/dmtf6n27/38/

Please also note there is a difference for the keycode numbers, whether you are using onkeypress or onkeyup. More info here: w3 schools KeyboardEvent keyCode Property

//For single key: Short cut key for 'Z'document.onkeypress = function (e) {    var evt = window.event || e;    switch (evt.keyCode) {        case 90:              // Call your method Here            break;    }}//For combine keys like Alt+Pdocument.onkeyup = function (e) {    var evt = window.event || e;           if (evt.keyCode == 80 && evt.altKey) {            // Call Your method here           }    }}    //ensure if short cut keys are case sensitive.    //    If its not case sensitive then    //check with the evt.keyCode values for both upper case and lower case. ......