JavaScript (Have one button open and close something)
<p>I currently have a hamburger menu and when you click on the hamburger, it will turn into an x. I want it so that when you click on the hamburger, it will open the menu and if you click the x, it will close the menu.</p>

<p>This is my code so far.</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;style&gt;
body {
    font-family: "Lato", sans-serif;
}

.sidenav {
    height: 100%;
    width: 0;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: #111;
    overflow-x: hidden;
    transition: 0.5s;
    padding-top: 60px;
}

.sidenav a {
    padding: 8px 8px 8px 32px;
    text-decoration: none;
    font-size: 25px;
    color: #818181;
    display: block;
    transition: 0.3s
}

.sidenav a:hover, .offcanvas a:focus{
    color: #f1f1f1;
}

.closebtn {
    position: absolute;
    top: 0;
    right: 25px;
    font-size: 36px !important;
    margin-left: 50px;
}

#main {
    transition: margin-left .5s;
    padding: 16px;
}

@media screen and (max-height: 450px) {
  .sidenav {padding-top: 15px;}
  .sidenav a {font-size: 18px;}
}
.container {
    display: inline-block;
    cursor: pointer;
}

.bar1, .bar2, .bar3 {
    width: 35px;
    height: 5px;
    background-color: #333;
    margin: 6px 0;
    transition: .9s;
}

.change .bar1 {
    -webkit-transform: rotate(-45deg) translate(-9px, 6px) ;
    transform: rotate(-45deg) translate(-9px, 6px) ;
}

.change .bar2 {opacity: 0;}

.change .bar3 {
    -webkit-transform: rotate(45deg) translate(-8px, -8px) ;
    transform: rotate(45deg) translate(-8px, -8px) ;
}
&lt;/style&gt;
&lt;body&gt;

&lt;div id="mySidenav" class="sidenav"&gt;

  &lt;a href="#"&gt;...&lt;/a&gt;
  &lt;a href="#"&gt;...&lt;/a&gt;
  &lt;a href="#"&gt;...&lt;/a&gt;
  &lt;a href="#"&gt;...&lt;/a&gt;
&lt;/div&gt;

&lt;div id="main"&gt;
  &lt;span style="cursor:pointer" onclick="openNav(); closeNav()&gt;
&lt;div class="container" onclick="myFunction(this)"&gt;
  &lt;div class="bar1"&gt;&lt;/div&gt;
  &lt;div class="bar2"&gt;&lt;/div&gt;
  &lt;div class="bar3"&gt;&lt;/div&gt;
&lt;/div&gt;
&lt;/span&gt;
&lt;/div&gt;

&lt;script&gt;
function openNav() {
    document.getElementById("mySidenav").style.width = "250px";
    document.getElementById("main").style.marginLeft = "250px";
}

function closeNav() {
    document.getElementById("mySidenav").style.width = "0";
    document.getElementById("main").style.marginLeft= "0";
}
function myFunction(x) {
    x.classList.toggle("change");
}
&lt;/script&gt;

&lt;/body&gt;
&lt;/html&gt;
</code></pre>