html - Image reveal game javascript -

hi new javascript , have make game.

my game involves finding animals hiding behind objects in space of 60 seconds. objects images , have created them divs.

i need hide image of animal behind object when player clicks on object animal appears. going use alert not sure if that's best approach.

example of code: html:

<div id ="clown">    <img src="clown.png" width="300" height="250"> </div> 

javascript: clown = document.getelementbyid('clown')

so understand, want 2 types of images displayed: object , animal, animal hidden default , revealed when object clicked.

this can done using css , javascript shown in example below.

<style> #object .animal {     position: absolute;     left:0;     top:0;     visibility:hidden; } </style>   <div id="object"> <img class="animal" src="animalimgsrc"> <img src="objimgsrc"> </div>   <script> document.getelementbyid("object").onclick = function(){     document.getelementbyid("object").getelementsbyclassname("animal")[0].style.visibility = "visible"; }; </script> 

i guess, need make "object" class instead of id, if want multiple objects.