<!DOCTYPE html>
<html lang="en">
<head>
<style>
div{
display: inline-block;
width: 30px;
height: 30px;
border: 1px solid red;
}
</style>
</head>
<body>
<div class="element">-</div>
<div class="element">-</div>
<div class="element">-</div>
<div class="element">-</div>
<script>
[].forEach.call(document.querySelectorAll('.element'), function(el){
el.onclick=function(){
el.innerHTML = Math.floor(Math.random() * 9);
};
});
</script>
</script>
</body>
</html>