Sidebar menu responsive bootstrap 4

Making dropdowns work

1. To make a drop-down menu collapsible, data-toggle="collapse" should be added to the link holding the dropdown.
2. Note that I also added class="dropdown-toggle" - this class adds a little triangle on the side and helps the user understand its function.
3. The link's href attribute must contain the id of the dropdown menu preceded by a hash. In this case, I used #homeSubmenu.
4. The dropdown menu itself also should have .collapse class too.

Pages

    

        Page 1
    
    

        Page 2
    
    

        Page 3
    

Be sure to add aria-expanded to the dropdown's control element Home

• Home 1
• Home 2
• Home 3

CSS

As we need a fixed height sidebar, we'll get rid of align-items property that stretched items vertically.

However the content extends, the sidebar still will take the entire viewport height. For this, we'll replace min-height: 100vh with height: 100vh. 

.wrapper {
    display: flex;
    width: 100%;
}

#sidebar {
    width: 250px;
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    z-index: 999;
    background: #7386D5;
    color: #fff;
    transition: all 0.3s;
}

At this point, we've finished all the CSS modifications.

We'll add two extra tricks in the JavaScript, let's have a look at them now.

JavaScript

The first trick is that I'll replace the default browser scrollbar in the side menu with a custom one.

We will need the scrollbar to appear just in cases when the navigation would be too high to fit in the viewport.

For this purpose, I'll use a jQuery custom content scroller.

Let's add its JS file to our HTML file first.

And its stylesheet file to the  element:

Now, let's initialize the plugin and use some of its options

$[document].ready[function [] {

    $["#sidebar"].mCustomScrollbar[{
         theme: "minimal"
    }];

    $['#sidebarCollapse'].on['click', function [] {
        $['#sidebar'].toggleClass['active'];
    }];

}];

The second trick we'll use is that I'll minimize the open dropdowns when the sidebar closes.

The reason for this is to keep things consistent and to open a navbar with closed dropdowns every time.

$[document].ready[function [] {

    $["#sidebar"].mCustomScrollbar[{
         theme: "minimal"
    }];

    $['#sidebarCollapse'].on['click', function [] {
        // open or close navbar
        $['#sidebar'].toggleClass['active'];
        // close dropdowns
        $['.collapse.in'].toggleClass['in'];
        // and also adjust aria-expanded attributes we use for the open/closed arrows
        // in our CSS
        $['a[aria-expanded=true]'].attr['aria-expanded', 'false'];
    }];

}];

To clarify what we have done here: 

The class .in is responsible for opening the dropdown menu. If the dropdown has one, it's open, if not, it's closed.

We told our JavaScript that if this class is present, please remove it. Also, please change the aria-expanded value from true to false so the arrow will return to its logical direction.

This makes our fixed sidebar navigation complete. Let's have a look at what we've built.

View Demo

3. Fixed scrollable sidebar menu with a content overlay

In this approach, we'll make a side navbar similar to the one that Google uses for its navbars on tablets and mobile phones in Material design. 

The sidebar will cover the left part of the page content when it's open and the rest of the content will be covered by a dark transparent overlay.

Home

• Home 1
• Home 2
• Home 3

CSS

The sidebar will have a fixed position at the left part of the screen, and the content will occupy the full screen all the time.

By default, the sidebar will be hidden.

When the toggle button is clicked, both .overlay and the sidebar will appear above the content.

Let's imagine it as layers. 

The page content will be the back layer, .overlay will be the middle layer with a transparent black color.

The overlay will cover the content of the page to allow the user's eye to easily focus on the sidebar itself.

Finally, the sidebar will be the front layer.

To achieve this layering behavior, we will simply use the z-index property.

As mentioned before, we will be also adding a  #dismiss button to the sidebar.

It will be positioned absolutely, at its top-right part.

.wrapper {
    display: block;
}

#sidebar {
    min-width: 250px;
    max-width: 250px;
    height: 100vh;
    position: fixed;
    top: 0;
    left: 0;
    /* top layer */
    z-index: 9999;
}

.overlay {
    display: none;
    position: fixed;
    /* full screen */
    width: 100vw;
    height: 100vh;
    /* transparent black */
    background: rgba[0, 0, 0, 0.7];
    /* middle layer, i.e. appears below the sidebar */
    z-index: 998;
    opacity: 0;
    /* animate the transition */
    transition: all 0.5s ease-in-out;
}
/* display .overlay when it has the .active class */
.overlay.active {
    display: block;
    opacity: 1;
}

#dismiss {
    width: 35px;
    height: 35px;
    position: absolute;
    /* top right corner of the sidebar */
    top: 10px;
    right: 10px;
}

JavaScript

In two previous sidebars, the toggle button functionality was to open/close the sidebar.

Here, we already have a close button inserted in our sidebar, so the toggle button function is only to open the sidebar.

To clarify the mechanism, by clicking the toggle button both overlay and sidebar appear, and by clicking the sidebar close button, both overlay and sidebar disappear.

    $[document].ready[function [] {
        $["#sidebar"].mCustomScrollbar[{
            theme: "minimal"
        }];

        $['#dismiss, .overlay'].on['click', function [] {
            // hide sidebar
            $['#sidebar'].removeClass['active'];
            // hide overlay
            $['.overlay'].removeClass['active'];
        }];

        $['#sidebarCollapse'].on['click', function [] {
            // open sidebar
            $['#sidebar'].addClass['active'];
            // fade in the overlay
            $['.overlay'].addClass['active'];
            $['.collapse.in'].toggleClass['in'];
            $['a[aria-expanded=true]'].attr['aria-expanded', 'false'];
        }];
    }];

This is it.

Time to check the demo.

View Demo

4. Partially collapsing static Bootstrap sidebar

In this example, we will, instead of building a sidebar that collapses entirely, build a Partially collapsing side navbar. The side menu will convert itself into a compressed version after the toggle button click.

Let's use the first examples's markup as a starting point.

Home

• Home 1
• Home 2
• Home 3

CSS

Instead of pushing the sidebar entirely out of the screen, we'll just shrink its width, and restyle its content to fit this new width.

The styles of the compressed version will be added to the class .active. 

For example, we will downsize the font size of the anchors' text, align it to the center, and make it render below the icon.

Also, we will move the arrow to the very bottom of every anchor, or adjust the padding around the dropdown links.

The code will be as follows:

/* Shrinking the sidebar from 250px to 80px and center aligining its content*/
#sidebar.active {
    min-width: 80px;
    max-width: 80px;
    text-align: center;
}

/* Toggling the sidebar header content, hide the big heading [h3] and showing the small heading [strong] and vice versa*/
#sidebar .sidebar-header strong {
    display: none;
}
#sidebar.active .sidebar-header h3 {
    display: none;
}
#sidebar.active .sidebar-header strong {
    display: block;
}

#sidebar ul li a {
    text-align: left;
}

#sidebar.active ul li a {
    padding: 20px 10px;
    text-align: center;
    font-size: 0.85em;
}

#sidebar.active ul li a i {
    margin-right:  0;
    display: block;
    font-size: 1.8em;
    margin-bottom: 5px;
}

/* Same dropdown links padding*/
#sidebar.active ul ul a {
    padding: 10px !important;
}

/* Changing the arrow position to bottom center position, 
   translateX[50%] works with right: 50% 
   to accurately  center the arrow */
#sidebar.active .dropdown-toggle::after {
    top: auto;
    bottom: 10px;
    right: 50%;
    -webkit-transform: translateX[50%];
    -ms-transform: translateX[50%];
    transform: translateX[50%];
}

Media queries

On smaller screens, we'll keep the compressed version as a default active state of the sidebar. I.e., the uncompressed version will not be used on mobiles at all and the compressed version will become visible after clicking the toggle button.

To achieve this, we can only copy the styles from .active to our  mobile media query @media [max-width: 768px]  and add a margin-left functionality to it.

For mobiles, #sidebar.active sidebar will have a negative left margin [it will be off the canvas] and the #sidebar without the .active class will have margin-left set to 0.

@media [max-width: 768px] {
    /* 80px and its content aligned to centre. Pushing it off the screen with the
       negative left margin
    */
    #sidebar.active {
        min-width: 80px;
        max-width: 80px;
        text-align: center;
        margin-left: -80px !important;
    }


    /* Reappearing the sidebar on toggle button click */
    #sidebar {
        margin-left: 0; 
    }


    /* Toggling the sidebar header content, 
       hide the big heading [h3] and showing the small heading [strong] and vice versa
    */
    #sidebar .sidebar-header strong {
        display: none;
    }
    #sidebar.active .sidebar-header h3 {
        display: none;
    }
    #sidebar.active .sidebar-header strong {
        display: block;
    }

    /* Downsize the navigation links font size */
    #sidebar.active ul li a {
        padding: 20px 10px;
        font-size: 0.85em;
    }

    #sidebar.active ul li a i {
        margin-right:  0;
        display: block;
        font-size: 1.8em;
        margin-bottom: 5px;
    }

    /* Adjust the dropdown links padding*/
    #sidebar.active ul ul a {
        padding: 10px !important;
    }

    /* Changing the arrow position to bottom center position, 
      translateX[50%] works with right: 50% 
      to accurately  center the arrow */
    .dropdown-toggle::after {
        top: auto;
        bottom: 10px;
        right: 50%;
        -webkit-transform: translateX[50%];
        -ms-transform: translateX[50%];
        transform: translateX[50%];
    }
}

JavaScript

We will not include any additional lines of JavaScript and we'll just use the same function did use in the first sidebar.

$[document].ready[function [] {

    $['#sidebarCollapse'].on['click', function [] {
        $['#sidebar'].toggleClass['active'];
    }];

}];

That will be all for now. We should have a nicely working partially collapsing sidebar.

Let's have a look at the results.

View Demo

Further Improvements

There is always room for further improvements and tweaks.

As a bonus, I would like to show you how to prepare an animated hamburger menu icon for the toggle button, and also how to add eye-catching animation for the opening and closing of the sidebar panel.

Home

 #sidebarCollapse {
    width: 40px;
    height: 40px;
    background: #f5f5f5;
}

#sidebarCollapse span {
    width: 80%;
    height: 2px;
    margin: 0 auto;
    display: block;
    background: #555;
    transition: all 0.8s cubic-bezier[0.810, -0.330, 0.345, 1.375];
}

#sidebarCollapse span:first-of-type {
    /* rotate first one */
    transform: rotate[45deg] translate[2px, 2px];
}
#sidebarCollapse span:nth-of-type[2] {
    /* second one is not visible */
    opacity: 0;
}
#sidebarCollapse span:last-of-type {
    /* rotate third one */
    transform: rotate[-45deg] translate[1px, -1px];
}

#sidebarCollapse.active span {
    /* no rotation */
    transform: none;
    /* all bars are visible */
    opacity: 1;
    margin: 5px auto;
}

.wrapper {
    display: flex;
    align-items: stretch;
    perspective: 1500px; 
}

#sidebar {
    min-width: 250px;
    max-width: 250px;
    background: #7386D5;
    color: #fff;
    transition: all 0.6s cubic-bezier[0.945, 0.020, 0.270, 0.665];
    transform-origin: center left; /* Set the transformed position of sidebar to center left side. */
}

#sidebar.active {
    margin-left: -250px;
    transform: rotateY[100deg]; /* Rotate sidebar vertically by 100 degrees. */
}

@media [max-width: 768px] {
    /* Reversing the behavior of the sidebar: 
       it'll be rotated vertically and off canvas by default, 
       collapsing in on toggle button click with removal of 
       the vertical rotation.   */
    #sidebar {
        margin-left: -250px;
        transform: rotateY[100deg];
    }
    #sidebar.active {
        margin-left: 0;
        transform: none;
    }

    /* Reversing the behavior of the bars: 
       Removing the rotation from the first,
       last bars and reappear the second bar on default state, 
       and giving them a vertical margin */
    #sidebarCollapse span:first-of-type,
    #sidebarCollapse span:nth-of-type[2],
    #sidebarCollapse span:last-of-type {
        transform: none;
        opacity: 1;
        margin: 5px auto;
    }

    /* Removing the vertical margin and make the first and last bars rotate again when the sidebar is open, hiding the second bar */
    #sidebarCollapse.active span {
        margin: 0 auto;
    }
    #sidebarCollapse.active span:first-of-type {
        transform: rotate[45deg] translate[2px, 2px];
    }
    #sidebarCollapse.active span:nth-of-type[2] {
        opacity: 0;
    }
    #sidebarCollapse.active span:last-of-type {
        transform: rotate[-45deg] translate[1px, -1px];
    }
}

$[document].ready[function [] {
    $['#sidebarCollapse'].on['click', function [] {
        $['#sidebar'].toggleClass['active'];
        $[this].toggleClass['active'];
    }];
}];