Thanks to anyone who helps me solve this issue.
So the issue is I'm trying to hide an element (by class) with an onclick event using a button. But I am unable to do so.
Here's the code on jsfiddle http://jsfiddle.net/1tpdgrnj/
Here's the code for those who wish to help me here:
HTML:
<div class="box">Hide on button click!!
<button onclick="close();">Close</button>
Javascript:
function close() {
document.getElementsByClassName("box").style.display = 'none';}
UPDATE
Refer to the answer below and to the jsfiddle to see how it's different.