How can I display an alert box when anyone access this code with any device except desktop or laptop?

Question

https://code.sololearn.com/WPXKz1IAUcxV/?ref=app

Answer 1

Add a media rule in CSS:

@media (min-width: 640px) {
body {
display: none;
}
}

would block all display for screen size above 640px

https://code.sololearn.com/Wal9OhWPmskR/?ref=app

Answer 2

For alert when it view by larger screen, add this JavaScript:

function checkScreenWidth() {
var maxWidth = 640;
if(screen.width>maxWidth) {
alert("The webpage is best view on mobile width of " + maxWidth + "px or less")
}
}

checkScreenWidth();

Answer 3

thank you