JSON APIs and Ajax: Change Text with click Events

Tell us what’s happening:

Why do I need that 0 in brackets? Why do I need to treat the element as an array? Isn’t it enough to identify it by the class name?

I tried that:

document.getElementsByClassName("message").innerHTML = "Here is the message"

But it is necessary to have the 0 in brackets. Why?

Sorry for the inconvenience, I appreciate your help.

Your code so far

document.addEventListener('DOMContentLoaded', function(){
  document.getElementById('getMessage').onclick = function(){
    // Add your code below this line
    document.getElementsByClassName("message")[0].textContent= "Here is the message"

    // Add your code above this line

body {
  text-align: center;
  font-family: "Helvetica", sans-serif;
h1 {
  font-size: 2em;
  font-weight: bold;
.box {
  border-radius: 5px;
  background-color: #eee;
  padding: 20px 5px;
button {
  color: white;
  background-color: #4791d0;
  border-radius: 5px;
  border: 1px solid #4791d0;
  padding: 5px 10px 8px 10px;
button:hover {
  background-color: #0F5897;
  border: 1px solid #0F5897;

<h1>Cat Photo Finder</h1>
<p class="message box">
The message will go here
<button id="getMessage">
  Get Message

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.162 Safari/537.36.

Challenge: Change Text with click Events

Link to the challenge:

As I understood, the 0 in brackets is because “getElementByClassName” returns an array so we have to specify that we want the first element (i.e. the 0 element), in this case there is only one element with the class message, but likewise, as “getElementByClassName” returns an array, we have to use the object notation.