Develop Reference

How to make my application to open the url when clicking the Alt button

I want to create my web application is more friendly to use. so I created a new functionalities like of if am want to move my page from current window to some other url, I am planing to press the 'ALT' Key.
I can able to get that functionality in my chrome as well as IE(11), the thing is its working properly in chrome and in IE, When keypress the page is going to the target but along with that the Browser Menus are also gets trigger.
How to control this browser behaviour
any my code is
$(function () {
var sar = false;
// Need to cancel event (only applies to IE)
if ( "onhelp" in window ) {
// (jQuery cannot bind "onhelp" event)
window.onhelp = function () {
return false;
};
}
$(document).keydown(function ( evt ) {
// Alt pressed
if ( evt.keyCode === 18 ) {
if ( window.event ) {
// Write back to IE's event object
window.event.keyCode = 0;
}
sar = true;
// Trigger custom help here
window.location.assign("http://www.google.com")
return false;
}
});
});
Here i attached the image of the trigger when i click the Alt button

Try this. It works for me in firefox and chrome.
$(document).on('keydown', function (evt) {
if ( evt.keyCode === 18 ) {
if ( window.event ) {
// Write back to IE's event object
window.event.keyCode = 0;
}
sar = true;
// Trigger custom help here
window.location.assign("http://www.google.com")
return false;
}
});

Detect mouse on touch screen device

I use the following code to detect whether the device is a touch device or not:
var isTouchDevice = 'ontouchstart' in window || navigator.msMaxTouchPoints;
if(isTouchDevice)
{
$('body').addClass('yes-touch');
}
else
{
$('body').addClass('no-touch');
}
I use this to only show :hover states when it is NOT a touch device (as most touch devices interpret a tap as a hover).
.no-touch .element:hover {
color: red;
}
The problem is, one of our PCs in the office is an all-on-one touch screen PC, which means that when using a mouse the hover states don't occur.
Is there a way to work out whether a mouse is being used on a touch screen device? In other words, it should have the no-touch class applied when the mouse is being used and the yes-touch class applied when the touch screen is being used.

As of today, there is no foolproof ironclad way of doing it. The modernizr folks, pretty much the experts in feature detection, recently had this to say about it:
https://github.com/Modernizr/Modernizr/issues/869#issuecomment-57891034
The end result of all of this is that you cannot detect a mouse use in
a way that would conform to the level of reliability that Modernizr is
credited with. For our intents and purposes, it is a undetectable.
If you, future traveler, wish to attempt to detect a mouse user, then
the following is the best guide I can offer.
Don't. Seriously. Just because a user has a "mouse" doesn't mean that
they don't have multiple other forms of input. You should try really
hard to avoid making any kind of UI/UX decision that changes based
upon the idea of a mouse user being diametrically opposed to a
touchscreen user (or any other kind, for that matter). Make things
universal.
If you have to, and only care about IE 10 and 11, then IE's
PointerEvent would be worth checking out. Support is abysmal, outside
of those two (and presumably future IE versions).
You can attach a
listener for a 'hover' event on the body, and if it is true, then the
user probably has a mouse. The drawback with this approach include
touch events briefly firing hover events on tap/touch, so you could
get false positives.
sniff for mobile user agents. This is a bad idea,
and goes against the very core of Modernizr. Please don't do it.
So to me #1 pretty much sums it up. However, that answers your question but doesn't give you a solution. You mention "one of our PC's in the office..." Is this by chance an internal only application? I've occasionally run across situations where internal special use or one off pages may require some individual treatment for whatever reason (like one of our employees having a touch based AIO with a mouse attached). What I'll do then is append a ?hasmouse onto the end of the url and give the user that link to bookmark. Then inside javascript after your var isTouchDevice but before your if, insert this code to undo it:
if (location.search == '?hasmouse') {
isTouchDevice = false;
}
Again, thats sort of a no frills way for just internal use.

I have been using this for a while and it seems to work reliably. I wounder if it's worth it sometimes, but it does work.
The idea here is to capture actual touchdown events to trigger touch mode and use mousemove to trigger mouse mode. The problem is IE does not trigger touch events, but pointer events. The great thing about pointer events is you can check if it's mouse or touch!
The problem is all other browsers fire a fake mousemove just after a touch event. It's truly maddening!
You can see it work on this codepen
//First check if this is a touch device:
this.isTouch = 'ontouchstart' in window || (navigator.msMaxTouchPoints > 0);
// Some vars we'll need later
var lastTouch = 0
var lastCheck = 0
//Then set up our event listeners:
function initEvents() {
//handle touch/mouse devices detect mouse so that touch is toggled off
if (this.isTouch) {
$(document).on(" touchstart mousemove " + msPointerEvent('move'), function(e) {
e = e.originalEvent
//browser has pointer events
var pe = window.PointerEvent || window.MSPointerEvent
// handle ie pointer events (polyfill functions are at bottom of answer)
if (e.type == msPointerEvent('move')) {
var touchEvent = msPointerType(e) == 'touch'
if (touchEvent)
lastTouch = e.timeStamp;
if (!this.isTouch && touchEvent)
return setupTouch.call(this, true)
else if (this.isTouch && !touchEvent)
return setupTouch.call(this, false)
}
// Handle all other browser touch events
if (e.type == "touchstart") {
console.log('touchstart fired')
lastTouch = e.timeStamp;
if (!this.isTouch)
setupTouch.call(this, true);
}
// test mouse move and set up mouse mode if real
else if (!pe && e.type == "mousemove" && this.isTouch) {
if (realMouseDown.call(this, e)) {
setupTouch.call(this, false)
}
}
}.bind(this));
}
}
initEvents()
// Here is where we get clever. It turns out that the fake mousemove will fire in less than 500ms of the touch so we use that to detect fakes. Then of course do something special for IE:
function realMouseDown(e) {
var touchDif = e.timeStamp - lastTouch
var mouseDif = e.timeStamp - lastCheck
// false mouse event will get fired within 500ms of a touch (touchDif > 500)
// (required for all browsers false mouse after touch event)
var real = touchDif > 500
lastCheck = e.timeStamp;
console.log('real=', real, ' mDif ='+mouseDif, ' tDif ='+touchDif)
return real
}
// Now for some IE polyfill because they cant seem to make up their mind what to do.
// IE pointer event polyfill
function msPointerEvent(type) {
var n = ""
if (window.PointerEvent) // IE 11
n = 'pointer' + type
else if (window.MSPointerEvent) // IE 10
n = 'MSPointer' + type[0].toUpperCase() + type.substr(1);
return n
}
// IE pointer type polyfill
function msPointerType(e) {
var pt = ['zero', 'one', 'touch', 'pen', 'mouse']
return typeof e.pointerType == 'string' ? e.pointerType : pt[e.pointerType]
}
// And finally do what you need...
// make required changes for touch / mouse
var $output = $('#output')
function setupTouch(state) {
console.log('TouchMode=', state)
if (state)
this.isTouch = true
else
this.isTouch = false
$output.html('Touch mode changed to = '+state)
}
//First check if this is a touch device:
this.isTouch = 'ontouchstart' in window || (navigator.msMaxTouchPoints > 0);
// Some vars we'll need later
var lastTouch = 0
var lastCheck = 0
//Then set up our event listeners:
function initEvents() {
//handle touch/mouse devices detect mouse so that touch is toggled off
if (this.isTouch) {
$(document).on(" touchstart mousemove " + msPointerEvent('move'), function(e) {
e = e.originalEvent
//browser has pointer events
var pe = window.PointerEvent || window.MSPointerEvent
// handle ie pointer events (polyfill functions are at bottom of answer)
if (e.type == msPointerEvent('move')) {
var touchEvent = msPointerType(e) == 'touch'
if (touchEvent)
lastTouch = e.timeStamp;
if (!this.isTouch && touchEvent)
return setupTouch.call(this, true)
else if (this.isTouch && !touchEvent)
return setupTouch.call(this, false)
}
// Handle all other browser touch events
else if (e.type == "touchstart") {
console.log('touchstart fired')
lastTouch = e.timeStamp;
if (!this.isTouch)
setupTouch.call(this, true);
}
// test mouse move and set up mouse mode if real
else if (!pe && e.type == "mousemove" && this.isTouch) {
if (realMouseDown.call(this, e)) {
setupTouch.call(this, false)
}
}
}.bind(this));
}
}
initEvents()
// Here is where we get clever. It turns out that the fake mousemove will fire in less than 500ms of the touch so we use that to detect fakes:
function realMouseDown(e) {
var touchDif = e.timeStamp - lastTouch
var mouseDif = e.timeStamp - lastCheck
// false mouse event will get fired within 500ms of a touch (touchDif > 500)
// (required for all browsers false mouse after touch event)
var real = touchDif > 500
lastCheck = e.timeStamp;
console.log('real=', real, ' mDif =' + mouseDif, ' tDif =' + touchDif)
return real
}
// IE pointer event polyfill
function msPointerEvent(type) {
var n = ""
if (window.PointerEvent) // IE 11
n = 'pointer' + type
else if (window.MSPointerEvent) // IE 10
n = 'MSPointer' + type[0].toUpperCase() + type.substr(1);
return n
}
// IE pointer type polyfill
function msPointerType(e) {
var pt = ['zero', 'one', 'touch', 'pen', 'mouse']
return typeof e.pointerType == 'string' ? e.pointerType : pt[e.pointerType]
}
// make required changes for touch / mouse
var $output = $('#output')
function setupTouch(state) {
console.log('TouchMode=', state)
if (state) {
this.isTouch = true
$output.addClass('is-touch')
} else {
this.isTouch = false
$output.removeClass('is-touch')
}
$output.html('Touch mode changed to = ' + state)
}
body {
pointer-evetns: none;
}
#output.is-touch {
background-color: blue;
color: white;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="output">
Touch or movethe mose on the result window to change the TouchMode state.
</div>

You can check for type of Pointer Event, that attached to Your object.
Please see example for hover below:
$('.element').on('pointerenter', function (e) {
if (e.pointerType == 'mouse') {
$(this).addClass('hover');
}
}).on('pointerleave', function (e) {
if (e.pointerType == 'mouse') {
$(this).removeClass('hover');
}
});
And use your css:
.element.hover {
color: red;
}

Keypress don't work on some Android devices

I have issue with Android in jQuery Terminal, I've almost fix it, it work on devices I've tested. Demo. But it seems that keypress event don't fire at all (It should echo keypress) on some devices.
On mobile I have code that keep focus on textarea (I resued clipboard) so virtual keyboard is open.
I have this code in keydown:
function keydown_event(e) {
...
if (enabled) {
...
} else {
// this get fired while typing
$.terminal.active().echo('keydown else');
prevent_keypress = false;
return;
}
// this will prevent for instance backspace to go back one page
prevent_keypress = true;
$.terminal.active().echo('keydown return false');
return false;
}
...
}
}
and in keypress:
var doc = $(document.documentElement || window);
doc.bind('keypress.cmd', function(e) {
var result;
if (e.ctrlKey && e.which === 99) { // CTRL+C
return;
}
// this line never get fired while typing
$.terminal.active().echo('keypress');
if (prevent_keypress) {
$.terminal.active().echo('prevent');
return;
}
if (!reverse_search && $.isFunction(options.keypress)) {
result = options.keypress(e);
}
if (result === undefined || result) {
...
self.insert(String.fromCharCode(e.which));
...
} else {
return result;
}
}).bind('keydown.cmd', keydown_event);
Anybody had same issue and know how to fix it, it's hard for me because it work on my devices.
UPDATE I've create simple test to isolate the problem and it seems that keypress is not fired at all.

I manage to fix (almost) the issue by detecting if keypress was not fired and get value from clipboard (for mobile the content it's always the same as terminal input)
var no_keypress;
doc.bind('keydown.cmd', function(e) {
no_keypress = true;
...
}).bind('keypress.cmd', function(e) {
no_keypress = false;
...
}).bind('keyup.cmd', function() {
if (no_keypress) {
// Some Androids don't fire keypress - #39
self.set(clip.val());
}
});

HTML5 FullScreen API toggle with JavaScript

I am trying to make a button that would toggle (on/off) HTML5 fullscreen on a certain website.
After reading plenty of documentation, it appears there still are some inconsistencies among how browsers treat certain properties for it.
I went for kind of "cross-browser" approach which does work in Firefox and Safari/MacOS, partially works in Safari/Windows and totally fails to work in Chrome and Opera.
Some castrated code snippets:
// class init
initialize: function() {
this.elmButtonFullscreen = $('fullscreen');
this.elmButtonFullscreen.on('click', this.onClickFullscreen.bindAsEventListener(this));
},
// helper methods
_launchFullScreen: function(element) {
if(element.requestFullScreen) { element.requestFullScreen(); }
else if(element.mozRequestFullScreen) { element.mozRequestFullScreen(); }
else if(element.webkitRequestFullScreen) { element.webkitRequestFullScreen(); }
},
_cancelFullScreen: function() {
if(document.cancelFullScreen) { document.cancelFullScreen(); }
else if(document.mozCancelFullScreen) { document.mozCancelFullScreen(); }
else if(document.webkitCancelFullScreen) { document.webkitCancelFullScreen(); }
},
_isFullScreen: function() {
fullScreen = document.fullscreenEnabled || document.mozFullscreenEnabled || document.webkitFullscreenEnabled ? true : false;
if(this.debug) console.log('Fullscreen enabled? ' + fullScreen);
return fullScreen;
},
// callbacks
onClickFullscreen: function(e) {
e.stop();
if(this._isFullScreen()) this._cancelFullScreen();
else this._launchFullScreen(document.documentElement);
}

function goFullScreen() {
const el = document.documentElement,
rfs = el.requestFullScreen
|| el.webkitRequestFullScreen
|| el.mozRequestFullScreen
|| el.msRequestFullscreen
rfs.call(el)
}
document.querySelector('#full-screen-button')
.addEventListener('click', () => {
goFullScreen()
})
Keep in mind that requesting fullScreen needs to be done via a user-triggered event such as a click event - mousedown,mouseup etc..

Changing the 1st line of _isFullScreen function to
fullScreen = document.fullscreenEnabled || document.mozFullscreenEnabled || document.webkitFullscreenEnabled ? true : false;
Does the trick (at least for Firefox, Chrome and Safari on Mac and Windows)

Based on what I found on Mozilla's Developer Network the function for Webkit is actually spelt slightly different.
document.webkitRequestFullscreen with a lowercase "s" for screen.
And from W3 spec, it is meant to be with a lowercase "s".
On the MDN link they say:
Note: The specification uses the label, "Fullscreen" as in "requestFullscreen" or "fullscreenEnabled" - without a capital 's'. The implementation described here and other prefixed implementations may use a capital 'S'.

Javascript to detect if user changes tab

I am writing a webpage for online quiz. The basic requirement I have is that it must fire an event(stopping the quiz) if the user changes tabs or opens a news window even without minimizing their browser, i.e if the person is attempting to see the answer from some other window/tab. How can I do that?
Note : Try to avoid including a bleeding edge HTML5 feature in your answer because I want the feature to be supported by all major browsers currently.

You can determine if a tab or window is active by attaching a blur / focus event listener to window.
in jQuery it would be
$(window).focus(function() {
//do something
});
$(window).blur(function() {
//do something
});
quoted from this SO answer: https://stackoverflow.com/a/1760268/680578

In 2022 you can use an event listener with the visibilitychange event:
document.addEventListener("visibilitychange", (event) => {
if (document.visibilityState == "visible") {
console.log("tab is active")
} else {
console.log("tab is inactive")
}
});

If you are targeting browsers that support it, you can use the Page Visibility API available in HTML5. It doesn't directly detect tab changes, per-say, but visibility changes. Which would include (but not limited to) tab changes.
See https://developer.mozilla.org/en/DOM/Using_the_Page_Visibility_API

Best native function hands down, no jQuery.
document.hasFocus
Check the pen, check what happens when you go to the link and back to the codepen tab.
https://codepen.io/damianocel/pen/Yxxzdj

With jQuery:
$(window).on('focus', function () {
});
$(window).on('blur', function () {
});
$().focus & $().blur are deprecated.

window onfocus and onblur work just fine:
window.onfocus = function (ev) {
console.log("gained focus");
};
window.onblur = function (ev) {
console.log("lost focus");
};

Working on a similar project. This worked the best. On the highest level component which wouldn't normally rerender, add:
setInterval( checkFocus, 200 );
function checkFocus(){
if(document.hasFocus()==false){
//Do some checking and raise a red flag if this runs during an exam.
}
}

I needed something like this and it seems this behavior is slightly different on each browser.
if (document.hidden !== undefined) { // Opera 12.10 and Firefox 18 and later support
visibilityChange = "visibilitychange";
} else if (document.mozHidden !== undefined) {
visibilityChange = "mozvisibilitychange";
} else if (document.msHidden !== undefined) {
visibilityChange = "msvisibilitychange";
} else if (document.webkitHidden !== undefined) {
visibilityChange = "webkitvisibilitychange";
} else if (document.oHidden !== undefined) {
visibilityChange = "ovisibilitychange";
}
document.addEventListener(visibilityChange, function(event) {
handleVisibilityChange();
}, false);
I have an example you can check:
https://jsfiddle.net/jenol/4g1k80jq/33/