r1sus,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body>
<input class="plus" type="button" value="+" > <p class="count">1</p>
<input class="plus" type="button" value="+" > <p class="count">1</p>
<script>
window.addEventListener('DOMContentLoaded', function() {
var p = document.querySelectorAll('.count');
[].forEach.call(document.querySelectorAll('.plus'), function(input,i) {
input.addEventListener('click', function() {
p[i].innerHTML -= -1
});
});
});
</script>
</body>
</html>