Is it possible to detect a battery operated device in javascript? - javascript

A client recently asked me to implement a slideshow on our website. I'm concerned that constantly animating picture transitions on the homepage will peg the processor of most mobile devices, so I want to disable the automatic advancing to preserve battery life. Is there any way to do this without trying to detect the user agent?
I've seen that there is a battery status API drafted here, but I don't know how complete it is, or which browsers have implemented it.

Actually determining battery would be quite difficult and probably involve various permissions problems.
Try just executing a small piece of code and checking the time it took. Pick a cutoff and if the code executes too slowly, turn off the transitions/animation/autoadvance. This will catch more than just battery devices; anything too slow will get the un-animated version. Degrade gracefully.

Now you can, with this API: http://davidwalsh.name/javascript-battery-api
navigator.getBattery().then(function(result) {});

Another old topic, but still relevant - I now check if the device has motion sensors, not many laptops do, but all modern smart phones and tablets do - so laptop users can live with slightly more battery use -
jQuery:
if (window.DeviceOrientationEvent) {
$(window).one("devicemotion", function(event) {
if (event.originalEvent.acceleration
&& event.originalEvent.acceleration.x !== null) { // Chrome fakes it on desktop
isMobile = true;
}
});
}
Plain Javascript:
if (window.DeviceOrientationEvent) {
window.ondevicemotion = function(event) {
if (event.acceleration
&& event.acceleration.x !== null) { // Chrome fakes it on desktop
window.ondevicemotion = null;
isMobile = true;
}
};
}

Related

absolute device orientation on mobile devices

I am trying to get the absolute device orientation across different mobile devices (android + IOs) and browsers
in a more or less reliable way. I would rather be able to understand if the orientation I am receiving is relative and not show the compass instead of showing wrong values.
I have been googling back and forth for days and I haven't found a definitive answer yet (I am
a javascript and web dev novice).
I see that the Full-Tilt library should be doing exactly
that but it has a non commercial license. I intend to use this result in a potentially commercial project, moreover, I would like to understand what's happening.
Nowadays most deviceorientation events are returning relative values.
deviceorientationabsolute is not supported by firefox and it's an experimental feature, I can fallback on it when other things fail but it cannot be the main solution.
So far I've got to this line of reasoning (pseudocode):
if(mobile)
if(webkitmobilecompassheading)
window.addEventListener("deviceorientation", handleOrientationWebkit, true);
else if(deviceorientationabsolute)
window.addEventListener("deviceorientation", handleOrientationAbsolute, true);
else
"bad luck"
I have no idea where to look to understand how many devices I would miss out on with the following reasoning, and if there is a better way.
For Android it works auto, for iOS it needs to be clicked to start it.
Here's a part of code you can use for that
startBtn.addEventListener("click", startCompass);
function startCompass() {
if (isIOS) {
DeviceOrientationEvent.requestPermission()
.then((response) => {
if (response === "granted") {
window.addEventListener("deviceorientation", handler, true);
} else {
alert("has to be allowed!");
}
})
.catch(() => alert("not supported"));
} else {
window.addEventListener("deviceorientationabsolute", handler, true);
}
}
function handler(e) {
const degree = e.webkitCompassHeading || Math.abs(e.alpha - 360);
}
Full tutorial is here, try demo also
https://dev.to/orkhanjafarovr/real-compass-on-mobile-browsers-with-javascript-3emi

Detect if console/devtools is open in all browsers

I'm trying to create a script which will run when any browser console is opened or closed. Is there any way to detect if the browser console in all browsers (Firefox/IE/Chrome/Safari/Opera) is open or not via JavaScript, jQuery, or any other client-side script?
If you are willing to accept an interference for the user,
you could use the debugger statement, as it is available in all major browsers.
Side note: If the users of your app are interested in console usage, they're probably familiar with dev tools, and will not be surprised by it showing up.
In short, the statement is acting as a breakpoint, and will affect the UI only if the browser's development tools is on.
Here's an example test:
<body>
<p>Devtools is <span id='test'>off</span></p>
<script>
var minimalUserResponseInMiliseconds = 100;
var before = new Date().getTime();
debugger;
var after = new Date().getTime();
if (after - before > minimalUserResponseInMiliseconds) { // user had to resume the script manually via opened dev tools
document.getElementById('test').innerHTML = 'on';
}
</script>
</body>
devtools-detect should do the job. Try the simple demo page.
devtools-detect → detect whether DevTools is open, and its orientation.
Supported Browsers:
DevTools in Chrome, Safari, Firefox & Opera
Caveats:
Doesn't work if DevTools is undocked (separate window), and may show a false positive if you toggle any kind of sidebar.
I don't think it is directly possible in JS for security reasons.But in here
they are claiming that it is possible and is useful for when you want something special to happen when DevTools is open. Like pausing canvas, adding style debug info, etc.
But As #James Hill tell in this, I also thinks even if a browser chose to make this information accessible to the client, it would not be a standard implementation (supported across multiple browsers).
Also can also try this one also here.
It's not possible in any official cross browser way, but if the occasional false positive is acceptable, you can check for a window.onresize event. Users resizing their windows after loading a page is somewhat uncommon. It's even more effective if you expect users will be frequently opening the console, meaning less false positives as a percentage.
window.onresize = function(){
if ((window.outerHeight - window.innerHeight) > 100) {
// console was opened (or screen was resized)
}
}
Credit to https://stackoverflow.com/a/7809413/3774582. Although that question is chrome specific, the concept applies here.
To expand on this, if you need a very low tolerance on false positives, most window resizes will trigger this event dozens of times because it is usually done as a drag action, while opening the console will only trigger this once. If you can detect this, the approach will become even more accurate.
Note: This will fail to detect if the console is already open when the user visits the page, or if the user opens the console in a new window.
(function() {
'use strict';
const el = new Image();
let consoleIsOpen = false;
let consoleOpened = false;
Object.defineProperty(el, 'id', {
get: () => {
consoleIsOpen = true;
}
});
const verify = () => {
console.dir(el);
if (consoleIsOpen === false && consoleOpened === true) {
// console closed
window.dispatchEvent(new Event('devtools-opened'));
consoleOpened = false;
} else if (consoleIsOpen === true && consoleOpened === false) {
// console opened
window.dispatchEvent(new Event('devtools-closed'));
consoleOpened = true;
}
consoleIsOpen = false;
setTimeout(verify, 1000);
}
verify();
})();
window.addEventListener('devtools-opened', ()=>{console.log('opened')});
window.addEventListener('devtools-closed', ()=>{console.log('closed')});
Here is a code that worked for me.
This solution works like a charm
https://github.com/sindresorhus/devtools-detect
if you are not using modules - disable lines
// if (typeof module !== 'undefined' && module.exports) {
// module.exports = devtools;
// } else {
window.devtools = devtools;
// }
and result is then here
window.devtools.isOpen
I for my project use the blur event.
function yourFunction() {}
window.addEventListener('blur',(e)=>{e.preventDefault(); yourFunction()})
This will execute yourFunction when the window loses focus.
For instance when someone opens the DevTools.
Okay seems like it also fires when you try to access a different window... so maybe not the best solution.
Maybe pair it with looking at the width of the browser.
If it chainged you can be pretty sure about it I think

Latest Desktop Firefox recognized as touch device?

has anyone noticed that on the last version of Desktop Firefox, it is recognized as a touch device?
I am using the script below:
function isTouch() {
try{ document.createEvent("TouchEvent"); return true; }
catch(e){ return false;
}
}
if (isTouch()) {
alert('I am touch device!')
}
The script has given me flawless results up until the latest version of Desktop Firefox. Is it a bug? Am I missing something?
Thanks everyone for your time!
edit: False alarm people. I have no idea what went wrong, I tried resetting preferences, disabled all extensions but had no luck.
I finally solved the issue by REFRESHING firefox (lost all my extensions though and had to reinstall).
Thanks for everybody's efforts and sorry for any inconvenience caused.
You are just checking if you can create a specific type of event, not really if you are currently on a touch device.
Here is a more complete isTouchDevice function, which I wrote some time ago based on the core of Modernizr.
/**
* Detect if the current device is a touch device.
* Inspired by Modernizr and hardcore streamlined.
*/
function isTouchDevice() {
var bool;
if( ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch ) {
bool = true;
}
else {
var fakeBody = document.createElement( 'fakebody' );
fakeBody.innerHTML += '<style>#media (touch-enabled),(-webkit-touch-enabled),(-moz-touch-enabled),(-o-touch-enabled){#touchtest{top:42px;position:absolute}}</style>';
document.documentElement.appendChild( fakeBody );
var touchTestNode = document.createElement( 'div' );
touchTestNode.id = 'touchtest';
fakeBody.appendChild( touchTestNode );
bool = touchTestNode.offsetTop === 42;
}
return bool;
}
I've had a similar problem, and maybe some people will benefit from the information.
In my case, the Touch events were always detected as positive by Modernizr in Firefox desktop, even if they weren't fired.
In the end, I realized that 'dom.w3c_touch_events.enabled' had a value of '1' even if I didn't set it myself.
It was actually switched on by the "Touch" button in Responsive Design View, but never switched back to '0' even after disabling the Touch events with the very same button.
So I've reported a bug to Mozilla : https://bugzilla.mozilla.org/show_bug.cgi?id=1188270
You will find a test case there.
Basically, the only solution I had to go back to normal is to change manually the value of 'dom.w3c_touch_events.enabled' to '0' in 'about:config'.
And I'm now aware that by enabling Touch events in the Responsive Design View, I will have to manually switch it back after.
Hope this can help some people !

Detecting NON-mobile devices with JavaScript

Before voting for duplicate:
Please read the full question below. I explained there why any of "how to detect mobile device?" is not a case here.
Question (and why it's not a simple negation of mobile dev. detection):
There are plenty of questions about "How to detect an mobile device with JavaScript?" (one of the best, if you are looking for it: What is the best way to detect a mobile device in jQuery?), but I want to ask for something a bit different: "How to detect non-mobile device with JavaScript?".
You might think that when I can make an mobile detection like this:
if(/Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile
|Opera Mini/i.test(navigator.userAgent)){
alert('mobile');
}
I can just put negation before the statement inside if and that would be check for non-mobile device. Not really.
The code above detects several versions of mobile devices. For all not recognized devices, we cannot be 100% sure that they are not mobile. If userAgent contains one of the typed literals (webOS, iPone etc.) it's surely a mobile device. If not, it can goes two ways:
It's not a mobile device
It's a mobile device that we did not listed (mistake, exotic device, device released after we wrote the code etc.)
So instead of negating the test for mobile device, I want to write a test for non-mobile (Linux/Windows PC, Mac etc.). That way, if the result will be true, I will be 100% sure that I deal with non-mobile device. In the other case - it's rather mobile, but it's only an strong assumption.
So basically, I want to react only when I'm 100% sure it's non-mobile device, and when I do not know it for sure, I don't want to take any steps (or I will assume it's a mobile device).
How would that formula look? It's safe to test against Windows (Windows Phone or something like that could also use that literal?)? What about Mac, Linux PC and others?
This is taken from here:
var BrowserDetect = function() {
var nav = window.navigator,
ua = window.navigator.userAgent.toLowerCase();
// detect browsers (only the ones that have some kind of quirk we need to work around)
if (ua.match(/ipad/i) !== null)
return "iPod";
if (ua.match(/iphone/i) !== null)
return "iPhone";
if (ua.match(/android/i) !== null)
return "Android";
if ((nav.appName.toLowerCase().indexOf("microsoft") != -1 || nav.appName.toLowerCase().match(/trident/gi) !== null))
return "IE";
if (ua.match(/chrome/gi) !== null)
return "Chrome";
if (ua.match(/firefox/gi) !== null)
return "Firefox";
if (ua.match(/webkit/gi) !== null)
return "Webkit";
if (ua.match(/gecko/gi) !== null)
return "Gecko";
if (ua.match(/opera/gi) !== null)
return "Opera";
//If any case miss we will return null
return null;
};
It's not very elegant but you can add/remove it to your preference.
A second answer, while I understand you are specifically looking for a NON mobile detection, you could also use http://detectmobilebrowsers.com/ which has almost complete mobile device detection (Even the less popular).

How to detect whether device has a vibrator?

With navigator.vibrate one can make smartphones and tablets vibrate. However, the function is also available on desktop browsers, so its presence is not useful to detect whether a vibration motor is actually available.
Of course, I could check if the device is running a mobile OS for a decent approximation, but is there a proper way to detect whether vibration is actually available?
Reason: I'm using the vibration in a game, and include an on/off button for it. It makes no sense to show this button on a desktop PC.
Unfortunately, it sounds like you can't:
So apparently this is intentional, to avoid exposing accessibility
settings (which are seen as sensitive), to allow UAs to offer a
fallback, and potentially as a barrier to fingerprinting too.
From http://github.com/Modernizr/Modernizr/issues/1217
The spec itself says:
If pattern is an empty list, or if the device is unable to vibrate,
then return true and terminate these steps.
It seems impossible to detect if the device would actually vibrate somehow, so when I came to a similar problem I just used a fallback to sound if the OS seems not to be mobile device:
var navigatorTest = (function(ua){
return function(){
for(var i=0; i<arguments.length; ++i) {
if(ua.indexOf(arguments[i]) >= 0)
return true;
}
return false;
};
})(navigator.userAgent);
var bleep = ((
(navigatorTest("iPad", "iPod", "iPhone", "Android") || !navigatorTest("Macintosh", "Windows", "X11", "Linux"))
&& (navigator.vibrate || navigator.webkitVibrate || navigator.mozVibrate || navigator.msVibrate)
) || (
function(ctx){
return function(len){
var osc = ctx.createOscillator();
osc.connect(ctx.destination);
osc.start();
setTimeout(function(){
osc.stop();
}, len);
};
}
)(
window.AudioContext ? new AudioContext() : new webkitAudioContext()
)).bind(navigator, 300); // Vibration/bleep time
Although it is not what you mean (not a feature detection) it gives a fair fallback.

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