off canvas menu html css

Question

I want to make a off canvas menu like this but I shall push the text out of the screen and not crop. And I want to add a function that close the menu after I clicked out of it.

I got the code from w3school off canvas menu.

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";
}

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;
}

.sidenav .closebtn {
    position: absolute;
    top: 0;
    right: 25px;
    font-size: 36px;
    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;}
}

<div id="mySidenav" class="sidenav">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <a href="#">About</a>
  <a href="#">Services</a>
  <a href="#">Clients</a>
  <a href="#">Contact</a>
</div>

<div id="main">
  <h2>Sidenav Push Example</h2>
  <p>Click on the element below to open the side navigation menu, and push this content to the right.</p>
  <span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>
</div>

Answer 1

Rather than trying to add / remove CSS rules on the click events - try using a single function that adds / removes a class to achieve the opening / closing.

I create an open class that had the styling that you had in the js - then its just a case of adding / removing the class to allow the sidenav to open / close.

This is not how I would suggest to have it - but keeping it in touch with your original code as much as possible - I wrapped the entire thing in a div with an id of wrapper - and then said that on the click of that div (which contains the side nav and the main panel) that if the wrapper has the open class - then remove it (closing the sidenav) and if not - open it.

You will need to look at what you want to trigger the opening - I assume you don't want any click on the entire pain panel opening the side nave - but this should give you an idea on how to get a click outside of the sidenav to close it.

function toggleNav() {
  var wrapper = document.getElementById("wrapper");
  
  if(wrapper.classList.contains("open")){
    wrapper.classList.remove("open")
  } else {
    wrapper.classList.add("open");
  };
}

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;
}

.open #mySidenav {
  width:250px;  
}

.open #main {
  margin-left:250px;
}


.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;
}

.sidenav .closebtn {
    position: absolute;
    top: 0;
    right: 25px;
    font-size: 36px;
    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;}
}

<div id="wrapper" class="" onclick="toggleNav()">
<div id="mySidenav" class="sidenav">
  <a href="javascript:void(0)" class="closebtn">&times;</a>
  <a href="#">About</a>
  <a href="#">Services</a>
  <a href="#">Clients</a>
  <a href="#">Contact</a>
</div>

<div id="main">
  <h2>Sidenav Push Example</h2>
  <p>Click on the element below to open the side navigation menu, and push this content to the right.</p>
  <span style="font-size:30px;cursor:pointer">&#9776; open</span>
</div>
<div>