I am building a website specifically for mobile devices. There is one page in particular which is best viewed in landscape mode.
Is there a way to detect if the user visiting that page is viewing it in Portrait mode and if so, display a message informing the user that the page is best viewed in landscape mode? If the user is already viewing it in landscape mode then no message will appear.
So basically, I want the site to detect the viewport orientation, if orientation is Portrait, then display an alert message advising the user that this page is best viewed in Landscape mode.
if(window.innerHeight > window.innerWidth){
alert("Please use Landscape!");
}
jQuery Mobile has an event that handles the change of this property... if you want to warn if someone rotates later - orientationchange
Also, after some googling, check out window.orientation (which is I believe measured in degrees...)
EDIT: On mobile devices, if you open a keyboard then the above may fail, so can use screen.availHeight and screen.availWidth, which gives proper height and width even after the keyboard is opened.
if(screen.availHeight > screen.availWidth){
alert("Please use Landscape!");
}
You can also use window.matchMedia, which I use and prefer as it closely resembles CSS syntax:
if (window.matchMedia("(orientation: portrait)").matches) {
// you're in PORTRAIT mode
}
if (window.matchMedia("(orientation: landscape)").matches) {
// you're in LANDSCAPE mode
}
Tested on iPad 2.
David Walsh has a better and to the point approach.
// Listen for orientation changes
window.addEventListener("orientationchange", function() {
// Announce the new orientation number
alert(window.orientation);
}, false);
During these changes, the window.orientation property may change. A value of 0 means portrait view, -90 means a the device is landscape rotated to the right, and 90 means the device is landscape rotated to the left.