event.returnValue = false of an event - javascript

I am working on a scrollbar in Javascript. All works fine except for one problem. I notice that while dragging the scrollbar, if I move the mouse over the context that is being scrolled, the content gets selected. I don't want that to happen, so I used the preventDefault method from the event object, which worked perfectly for IE9 and the other modern browsers. But on IE7 and IE8, the problem persists. I did some searches and found that I should set the returnValue parameter of the event object to false. But the problem still persists. Also, if I write alert(window.event.returnValue) it pops up undefined.
scrollbar.onmousedown = function (event) {
if (typeof event == 'undefined') event = window.event;
if (typeof event.preventDefault != 'undefined') event.preventDefault();
event.returnValue = false;
// do some stuff
}
What am I doing wrong?

In IE7&8 there is no event Object as a parameter to the function, instead there exists window.event. Try
window.event.cancelBubble = true
to stop the propagation.
To avoid problems with FireFox etc. do something like this:
if (!event)
event = window.event;
//IE9 & Other Browsers
if (event.stopPropagation) {
event.stopPropagation();
}
//IE8 and Lower
else {
event.cancelBubble = true;
}

I fixed my problem in the end by adding event.returnValue = false in the 'onmousemove' event, instead on 'onmousedown' event and it worked. It doesn't answer the question about why the orginal code is wrong, but I wanted to post this for people that see my question, to not waste their time in trying to help me with a problem that I have already fixed. Thank you for your quick answers, I appreciate.

I too had the same problem.
preventDefault was not working in IE.
so I added the below code to stop propagation
if (a_event.preventDefault) {
a_event.preventDefault();
} else if (typeof a_event.returnValue !== "undefined") {
a_event.returnValue = false;
}

Related

Can I use both "onmousedown" and "ontouchstart" for a button? [duplicate]

Working on a website that is also viewable on mobile and need to bind an action on both touchstart and mousedown.
Looks like this
$("#roll").bind("mousedown touchstart", function(event){
someAction();
It works fine on Iphone, but on Android it responds twice.
event.stopPropagation();
event.preventDefault();
Adding this code fixed it for Android Chrome, but NOT for Android default browser. Any other tricks that can fix the problem for all android?
element.on('touchstart mousedown', function(e) {
e.preventDefault();
someAction();
});
preventDefault cancels the event, as per specs
You get touchstart, but once you cancel it you no longer get mousedown. Contrary to what the accepted answer says, you don't need to call stopPropagation unless it's something you need. The event will propagate normally even when cancelled. The browser will ignore it, but your hooks will still work.
Mozilla agrees with me on this one:
calling preventDefault() on a touchstart or the first touchmove event of a series prevents the corresponding mouse events from firing
EDIT: I just read the question again and you say that you already did this and it didn't fix the Android default browser. Not sure how the accepted answer helped, as it does the same thing basically, just in a more complicated way and with an event propagation bug (touchstart doesn't propagate, but click does)
I have been using this function:
//touch click helper
(function ($) {
$.fn.tclick = function (onclick) {
this.bind("touchstart", function (e) {
onclick.call(this, e);
e.stopPropagation();
e.preventDefault();
});
this.bind("click", function (e) {
onclick.call(this, e); //substitute mousedown event for exact same result as touchstart
});
return this;
};
})(jQuery);
UPDATE: Modified answer to support mouse and touch events together.
taking gregers comment on win8 and chrome/firefox into account, skyisred's comment doesn't look that dumb after all (:P # all the haters)
though I would rather go with a blacklist than with a whitelist which he suggested, only excluding Android from touch-binds:
var ua = navigator.userAgent.toLowerCase(),
isAndroid = ua.indexOf("android") != -1,
supportsPointer = !!window.navigator.msPointerEnabled,
ev_pointer = function(e) { ... }, // function to handle IE10's pointer events
ev_touch = function(e) { ... }, // function to handle touch events
ev_mouse = function(e) { ... }; // function to handle mouse events
if (supportsPointer) { // IE10 / Pointer Events
// reset binds
$("yourSelectorHere").on('MSPointerDown MSPointerMove MSPointerUp', ev_pointer);
} else {
$("yourSelectorHere").on('touchstart touchmove touchend', ev_touch); // touch events
if(!isAndroid) {
// in androids native browser mouse events are sometimes triggered directly w/o a preceding touchevent (most likely a bug)
// bug confirmed in android 4.0.3 and 4.1.2
$("yourSelectorHere").on('mousedown mousemove mouseup mouseleave', ev_mouse); // mouse events
}
}
BTW: I found that mouse-events are NOT always triggered (if stopPropagation and preventDefault were used), specifically I only noticed an extra mousemove directly before a touchend event... really weird bug but the above code fixed it for me across all (tested OSX, Win, iOS 5+6, Android 2+4 each with native browser, Chrome, Firefox, IE, Safari and Opera, if available) platforms.
Wow, so many answers in this and the related question, but non of them worked for me (Chrome, mobil responsive, mousedown + touchstart). But this:
(e) => {
if(typeof(window.ontouchstart) != 'undefined' && e.type == 'mousedown') return;
// do anything...
}
Fixed using this code
var mobile = /Android|webOS|iPhone|iPad|iPod|BlackBerry/i.test(navigator.userAgent);
var start = mobile ? "touchstart" : "mousedown";
$("#roll").bind(start, function(event){
This is a very old question but I came across the same problem and found another solution that does not stopPropagation(), preventDefault() or sniff the type of device. I work on this solution with the assumption that the device supports both touch and mouse inputs.
Explanation: When a touch is initiated, the order of events is 1) touchstart 2) touchmove 3) touchend 4) mousemove 5) mousedown 6) mouseup 7) click. Based on this, we will mark a touch interaction from touchstart (first in chain) until click (last in chain). If a mousedown is registered outside of this touch interaction, it is safe to be picked up.
Below is the logic in Dart, should be very replicable in js.
var touchStarted = false;
document.onMouseDown.listen((evt) {
if (!touchStarted) processInput(evt);
});
document.onClick.listen((evt) {
touchStarted = false;
});
document.onTouchStart.listen((evt) {
touchStarted = true;
processInput(evt);
});
As you can see my listeners are placed on document. It is thus crucial that I do not stopPropagation() or preventDefault() these events so they can bubble up to other elements. This solution helped me single out one interaction to act on and hope it helps you too!
I recommend you try jquery-fast-click. I tried the other approach on this question and others. Each fixed one issue, and introduced another. fast-click worked the first time on Android, ios, desktop, and desktop touch browsers (groan).
Write this code and add j query punch touch js.it will work simulate mouse events with touch events
function touchHandler(event)
{
var touches = event.changedTouches,
first = touches[0],
type = "";
switch(event.type)
{
case "touchstart": type = "mousedown"; break;
case "touchmove": type="mousemove"; break;
case "touchend": type="mouseup"; break;
default: return;
}
var simulatedEvent = document.createEvent("MouseEvent");
simulatedEvent.initMouseEvent(type, true, true, window, 1,
first.screenX, first.screenY,
first.clientX, first.clientY, false,
false, false, false, 0/*left*/, null);
first.target.dispatchEvent(simulatedEvent);
event.preventDefault();
}
function init()
{
document.addEventListener("touchstart", touchHandler, true);
document.addEventListener("touchmove", touchHandler, true);
document.addEventListener("touchend", touchHandler, true);
document.addEventListener("touchcancel", touchHandler, true);
}
This native solution worked best for me:
Add a touchstart event to the document settings a global touch = true.
In the mousedown/touchstart handler, prevent all mousedown events when a touch screen is detected: if (touch && e.type === 'mousedown') return;
I think the best way is :
var hasTouchStartEvent = 'ontouchstart' in document.createElement( 'div' );
document.addEventListener( hasTouchStartEvent ? 'touchstart' : 'mousedown', function( e ) {
console.log( e.touches ? 'TouchEvent' : 'MouseEvent' );
}, false );

jQuery - detect change event triggered programmatically

I have a jQuery change event for when a user changes a given SELECT element. However the event may also be triggered by a third party script. What I want to do is detect whether the event was triggered programmatically or by the user.
I have tried the accepted solution in this question Check if event is triggered by a human
But note the JSFiddle in this answer is for a click event rather than a change event.
To demonstrate I amended the fiddle and created this one: http://jsfiddle.net/Uf8Wv/231/
If you try this in latest Firefox or Chrome, you will see that the alert human is being shown even when the event was triggered programmatically.
I have tried event.originalEvent.isTrusted but that doesn't work in all browsers. Can anyone help?
I have added mouseenter and mouseleave events. The idea is that it's a human if the click coincided with a mousepointer being over the element. See:
http://jsfiddle.net/Uf8Wv/232/
$("#try").mouseenter(function(event) {
mouseover = true;
});
// ... etc.
I can't think of any other way.
You can find some vague difference between click and emulated click using this code:
$(document).on('change', "#try", function (event) {
//some difference appear in the next line
console.log(event.delegateTarget.activeElement);
//no difference
if (event.originalEvent === undefined) {
alert('not human')
} else {
alert(' human');
}
event.delegateTarget = null;//doesn't help
});
$('#click').click(function (event) {
$("#try").click();
});
Click on the checkbox logs <input id="try" type="checkbox">.
Click on the button logs <button id="click">.
But...
Run $("#try").click(); from console before any clicks logs <body> and after the click result of the last click.
Generally JS can always fake any client event. So isTrusted is never trusted.
You can listen to the click event as well, and modify a variable. The change event seems indeed to be quite similar wheter it's a real click or a script triggered click, but the click on #try event won't be the same. And since click is triggered before change, you have time to set a switch.
Like this for example:
var realClick;
$("#try").change(function(event) {
console.log('change')
if (!realClick) {
alert('not human')
} else {
alert(' human');
}
});
$("#try").click(function(event) {
console.log('click')
// originalEvent is one way, but there will be many differences
if (event.originalEvent) {
realClick = true;
} else {
realClick = false;
}
});
// Since this is called from outside, better not put
// any controls here.
$('#click').click(function(event) {
$("#try").click();
});
http://jsfiddle.net/2xjjmo09/3/
What really worked for me is:
if ((event.originalEvent.isTrusted === true && event.originalEvent.isPrimary === undefined) || event.originalEvent.isPrimary === true) {
//Hey hooman it is you
//Real CLick
}
Tested with jQuery version 3.5
You can easily detect whether the click event on the button is actually triggered by mouse click or not. By doing,
$('#click').click(function(ev) {
if (ev.which !== undefined && ev.button !== undefined) {
$("#try").click();
}
});
Here's the Fiddle
Note: Beware of either ev.which or ev.button could result in 0 on some browser for left-click.
You can check for if event.srcElement (which is source element on which event is triggered) is equal to event.currentTarget something like:
$("#try").change(function(event) {console.log(event,event.target,event.currentTarget,event.srcElement)
if (event.currentTarget=== event.srcElement) {
alert(' human')
} else {
alert(' not human');
}
});
Fiddle: http://jsfiddle.net/Uf8Wv/234/

keypress event not generated in chrome but works in ie and ff

This question has been asked plenty of times before, but no answers I have found seem to solve my problem.
From a classic asp page I call a Javascript function
on each of my pages. The point is to fire a search button when a user enters search text and presses enter, rather than clicking on the button, or choosing from the Ajax provided selections.
This works fine in IE and FF, as has been the case for every other question asked along these lines.
Here is the Javascript. Can anybody tell me please how to have it work for Chrome as well as IE and FF ?
Edited following answer form Alexander O'Mara below:
Altered function call in body tag on page to use onkeyup instead of onkeypress - onkeyup="KeyPress(event)"
Altered JS function (also after heeding comments re duplication from others - thanks) as follows:
function KeyPress(e)
{
var ev = e || window.event;
var key = ev.keyCode;
if(window.event) // IE
{
key = e.keyCode;
if (key == 13)
{
window.event.keyCode = 0;
$('#btnSearch').click();
}
}
else if (key == 13)
{
btnSearch.click();
ev.preventDefault();
}
}
It seems to work sometimes and not others, and rarely on chrome currently. Is there a guaranteed way to have it work all the time ?
The main page of my site if you want to try it yourself is www.dvdorchard.com.au, your cursor will be sitting in the search box on arrival - enter a word > 3 chars and press enter, if you stay on the page it didn't work, if you move to the productfound.asp page it worked.
Thanks again.
You are looking for the keyup event (documentation). The keypress event is not consistent across browsers. See this question for information on the differences.
Update:
Since you are using jQuery, you can also remove the onkeyup="KeyPress(event)" attribute for you body, and replace your KeyPress function with the following (replacing the contents with your event handling code).
$(window).keyup(function(e){
/*YOUR CODE HERE*/
});
if(e.keyCode)
{
key= e.keyCode;
}
else
{
key = e.charCode;
}
Fire your event with onkeyup
read more
this should work in chrome. I don't know about other browsers
function code(e) {
e = e || window.event;
return(e.keyCode || e.which);
}
window.onload = function(){
document.onkeypress = function(e){
var key = code(e);
// do something with key
// done doing something with key
key=0
};
};

Least amount of code to stop a link from firing (on all browsers)

When I want a function to stop a link and continue on executing my own code, I do this:
// IE
if (e.cancelBubble) {
e.cancelBubble = true;
}
// Firefox
if (e.stopPropagation) {
e.stopPropagation();
}
// Others
if (e.defaultPrevented) {
e.defaultPrevented();
}
alert('still executing my function');
Is all that really necessary, or could I do it with less code?
Simply make the function return false for javascript.
Since you mentioned in your comment you are using a jQuery click method, add the event.preventDefault().
$('#mylink').click(function(event) {
event.preventDefault();
//code here
})
jquery Source (thanks to BenjaminGreunbaum) for pointing out that jQuery normalizes events, thus event.returnValue is already handled.
For javascript, you'll want to add an eventListener.
function derp(event) {
event.preventDefault();
}
document.getElementById("mylink").addEventListener('click', derp, false);
You can use return false as it is effectively the same as calling both e.preventDefault and e.stopPropagation
e.preventDefault() will prevent the default event from occurring, e.stopPropagation() will prevent the event from bubbling up and return false will do both.
Write a simple return false; statement.
This will work in all browsers.

jqueryui - mouseMove function IE condition understanding

In my jquery-ui draggable I have this -
....
_mouseMove: function(event) {
// IE mouseup check - mouseup happened when mouse was out of window
if ($.browser.msie && !event.button) {
return this._mouseUp(event);
}
if (this._mouseStarted) {
this._mouseDrag(event);
return event.preventDefault();
}
if (this._mouseDistanceMet(event) && this._mouseDelayMet(event)) {
this._mouseStarted =
(this._mouseStart(this._mouseDownEvent, event) !== false);
(this._mouseStarted ? this._mouseDrag(event) : this._mouseUp(event));
}
return !this._mouseStarted;
},
....
Notice there is condition in the start for internet explorer. Now what is happening in my webpage is that dragging is not working for IE9 and IE10. It works for IE8, (I guess html markup errors have to do something regarding that and I am not worried about it). When I comment that condition dragging works in IE9 and IE10 i.e. I have found the fix for the problem I am facing. But as it is very high level javascript I here expecting a help from someone to explain me what is happening in the condition above.

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