Execute a code when multiple buttons are pushed

Question

I'm trying to execute some code when multiple buttons are pushed, I'm trying this as an example but it's not working :

    <script>

    var map = {82: false, 84: false};
    function keydown(e) {
        if (e.keyCode in map) {
            map[e.keyCode] = true;
            if (map[82] && map[84]) {
                alert(" all pressed ");
            }
        }
    }

    function keyup(e)
    {
        if (e.keyCode in map) {
            map[e.keyCode] = false;
        }
    }
    window.addEventListener('keyup', keyup);
    window.addEventListener('keydown', keydown);
    </script>

I get the alert even when only one button is pushed, ( i got it when both are pushed too )

What am i doing wrong please ?

[javascript multiple keys pressed at once](http://stackoverflow.com/a/12444641/3199927) — Tom, Feb 26 '15 at 18:28
possible duplicate of [javascript multiple keys pressed at once](http://stackoverflow.com/questions/5203407/javascript-multiple-keys-pressed-at-once) — Ejaz, Feb 26 '15 at 18:29

score 0 · Answer 1 · answered Feb 26 '15 at 18:31

0

You don't seem to be attaching your keyup handler, so once a key has been pressed it was forever marked as true in your map

window.addEventListener('keyup', keyup);

answered Feb 26 '15 at 18:31

Paul S.

64,864
9
122
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score 0 · Answer 2 · edited May 23 '17 at 12:06

0

Try this:

var map = []; 
onkeydown = onkeyup = function(e){
    e = e || event; // to deal with IE
    map[e.keyCode] = e.type == 'keydown';
    if(map[82] && map[84]){ 
        alert('all pressed');
    }
}

This was also already answered here:

JavaScript multiple keys pressed at once

Please make sure you check to avoid posting a duplicate question.

edited May 23 '17 at 12:06

Community

1
1

answered Feb 26 '15 at 18:51

Michał Zapatka

36
2

Same problem, it's working when I push both but also when I push only one of them – Othman Benchekroun Feb 26 '15 at 18:56
check it yourself, once you push both, you got the message but after that only one of them can get the alert – Othman Benchekroun Feb 26 '15 at 19:26

score 0 · Answer 3 · answered Feb 26 '15 at 19:37

0

I think I found the problem, the program doesn't execute the keyup fonction because of the alert, map[82] and map[84] are always true then.

answered Feb 26 '15 at 19:37

Othman Benchekroun

1,998
2
17
36

Execute a code when multiple buttons are pushed

3 Answers3