You can do it in css. You can use the @media to see if the screen size is smaller than that usually desktops have and by this you will be able to make your application responsive. Take a look at this code:
body {
--background-image: url('https://thumbs.dreamstime.com/b/vertical-banner-template-hands-typing-computer-office-supplies-distance-education-e-learning-obtaining-university-156390588.jpg');
margin: 0;
padding: 0;
box-sizing: border-box;
background-image: var(--background-image);
background-size: 100vw 100vh;
z-index: -1000;
}
#submit-form {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
height: 180px;
width: 300px;
background-color: white;
border-radius: 10px;
border: 2px dashed;
display: flex;
flex-direction: column;
align-items: center;
justify-content: space-around;
z-index: 1000;
}
#email-input {
height: 30px;
width: 220px;
border-radius: 10px;
}
#submit-button {
height: 30px;
width: 80px;
border-radius: 10px;
background-color: lightgreen;
border: 1px dashed;
}
@media all and (min-width: 1000px) {
body {
background-image: url('https://img.freepik.com/free-vector/online-education-students-view-lessons-through-mobile-devices-during-distance-learning_178888-361.jpg?w=2000');
}
#submit-form {
height: 250px;
width: 500px;
}
#email-input {
height: 50px;
width: 300px;
border-radius: 10px;
}
}
Here I am styling the sites for mobile devices first, and then, I am checking if the user is on a desktop and if he is, I am making the website responsive again.
This was for the styling part, but, what if you want to detect it in JavaScript?
You can use a simple function for this:
function findUserDevice() {
const isOnMobile = false;
if(window.innerWidth < window.innerHeight) {
isOnMobile = true;
}
return isOnMobile;
}
This is what I usually use, hope this was helpful!