<div id="welcomeDiv" style="display:none;" class="answer_list" > WELCOME</div>
<input type="button" name="answer" value="Show Div" onclick="showDiv('welcomeDiv')" />
<script>
function showDiv(Div) {
x=document.getElementById(Div);
if(x.style.display=="none"){
x.style.display = "block";
}
else{
document.getElementById(Div).style.display = "none";
}
}
</script>