I have the following script, that I found at w3schools,

<script>
var coll = document.getElementsByClassName("collapsible");
var i;

for (i = 0; i < coll.length; i++) {
  coll[i].addEventListener("click", function() {
    this.classList.toggle("active");
    var content = this.nextElementSibling;
    if (content.style.display === "block") {
      content.style.display = "none";
    } else {
      content.style.display = "block";
    }
  });
}
</script>

in order to make a toggle button for a text box. The problem is the script initially shows the text box and then hides it. I want to first hide and then show. Otherwise the initial first click doesn't do anything, so users will think, the button is broken.

To explain more, I use it with

    <button type="button" class="collapsible">Toggle document map</button>
    <div class="content">
    <p>bla..bla</p>
    </div>

and following css.

  .active, .collapsible:hover {
    background-color: #8511ae;
    color: white; font-weight: bold; text-decoration: underline;
}
  .collapsible {
    background-color: #faf9d8;
    color: #4e3fe3; font-style: italic; font-weight: bold;
    font-family: verdana, sans-serif;
    cursor: pointer;
    padding: 5px;
    width: 35%;
    float: left
    border: 0px solid #8511ae;
    text-align: center;
    outline: none;
    font-size: 15px;
    margin-top: 2%;
    margin-bottom: 0%;
    margin-left: 2%;
    margin-right: 24%;
}
  .content {
    width: 35%;
    float: left;
    padding: 0px;
    border: 0px solid #8511ae;
    margin-top: 0%;
    margin-bottom: 0%;
    margin-left: 2%;
    margin-right: 3%;
    background-color: #faf9d8;
}

The initial content css from w3schools, also includes

  display: none;
  overflow: hidden;

but since I want the text box to initially being visible when visiting the page, I left the above 2 items, out of the content css.

But now, as aforementioned, I have to click the toggle button twice (only the first time I do this) to hide the text box.

How can I modify the above javascript so that the first click hides instead of trying to make visible?

I tried some changes on my own but I just broke the script. This is the first website I ever made, and any help will be greatly appreciated.