1document.body.onkeyup = function(e){
2    if(e.keyCode == 32){
3        //your code
4    }
5}

1            
2var hits = 0;
3var hitElement = document.querySelector('.hits');
4document.body.onkeyup = function (e) {
5    if (e.keyCode == 32) {
6        addHit();
7    }
8}
9
10var addHit = function () {
11    hits++;
12    renderHits();
13}
14
15var renderHits = function () {
16    hitElement.innerHTML = hits;
17}
18
19var resetHits = function () {
20    hits = 0;
21    renderHits();
22}
23                
24        

1document.body.onkeyup = function(e){
2    if(e.key == ' '){
3        //your code
4    }
5}
6