Javascript touch event

In order to provide quality support for touch-based user interfaces, touch events offer the ability to interpret finger or stylus activity on touch screens or trackpads. The touch events interfaces are relatively low-level APIs that can be used to support application specific multi-touch interactions such as a two-finger gesture.

A multi-touch interaction starts when a finger or stylus first touches the contact surface. Other fingers may subsequently touch the surface and optionally move across the touch surface.

The interaction ends when the fingers are removed from the surface. During this interaction, an application receives touch events during the start, move and end phases.

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Touch events are similar to mouse events except they support simultaneous touches and at different locations on the touch surface. The TouchEvent interface encapsulates all of the touch points that are currently active. The Touch interface, which represents a single touch point, includes information such as the position of the touch point relative to the browser viewport.

The only way to detect touch with JavaScript

This example tracks multiple touch points at a time, allowing the user to draw in a element with either the canvas scripting API or the WebGL API to draw graphics and animations.

It will only work on a browser that supports touch events. When a touchstart event occurs, indicating that a new touch on the surface has occurred, the handleStart function below is called.

javascript touch event

This calls event. Then we get the context and pull the list of changed touch points out of the event's TouchEvent.

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After that, we iterate over all the Touch objects in the list, pushing them onto an array of active touch points and drawing the start point for the draw as a small circle; we're using a 4-pixel wide line, so a 4 pixel radius circle will show up neatly. Each time one or more fingers moves, a touchmove event is delivered, resulting in our handleMove function being called.

Its responsibility in this example is to update the cached touch information and to draw a line from the previous position to the current position of each touch. This iterates over the changed touches as well, but it looks in our cached touch information array for the previous information about each touch in order to determine the starting point for each touch's new line segment to be drawn.

This is done by looking at each touch's Touch. This property is a unique integer for each touch, and remains consistent for each event during the duration of each finger's contact with the surface. This lets us get the coordinates of the previous position of each touch and use the appropriate context methods to draw a line segment joining the two positions together.

After drawing the line, we call Array. When the user lifts a finger off the surface, a touchend event is sent. We handle this by calling the handleEnd function below. Its job is to draw the last line segment for each touch that ended and remove the touch point from the ongoing touch list.

This is very similar to the previous function; the only real differences are that we draw a small square to mark the end and that when we call Array. The result is that we stop tracking that touch point. If the user's finger wanders into browser UI, or the touch otherwise needs to be canceled, the touchcancel event is sent, and we call the handleCancel function below.

Since the idea is to immediately abort the touch, we simply remove it from the ongoing touch list without drawing a final line segment. This example uses two convenience functions that should be looked at briefly to help make the rest of the code more clear. In order to make each touch's drawing look different, the colorForTouch function is used to pick a color based on the touch's unique identifier. This identifier is an opaque number, but we can at least rely on it differing between the currently-active touches.

For example, for a Touch. The ongoingTouchIndexById function below scans through the ongoingTouches array to find the touch matching the given identifier, then returns that touch's index into the array.

If your browser supports it, you can see it live.You can think of it as how many separate fingers are able to be identified as touching the screen. This example illustrates the TouchEvent object's TouchEvent. The TouchEvent. In following code snippet, the touchstart event handler checks the length of the TouchEvent.

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Get the latest and greatest from MDN delivered straight to your inbox. Sign in to enjoy the benefits of an MDN account. Touch Events Recommendation Initial definition. Browser compatibility The compatibility table on this page is generated from structured data. Last modified: Jan 22,by MDN contributors. Related Topics. Learn the best of web development Get the latest and greatest from MDN delivered straight to your inbox.

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Sign up now. Sign in with Github Sign in with Google. Touch Events — Level 2. Touch Events. Chrome Full support IE No support No. Opera Full support Yes. Safari No support No. WebView Android Full support Yes. Chrome Android Full support Yes. Firefox Android Full support 6.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. How to detect a long touch pressure with javascript for android and iphone? The problem with using Touch End to detect the long touch is it won't work if you want the event to fire after a certain period of time. It is better to use a timer on touch start and clear the event timer on touch end. The following pattern can be used:.

Here is an extended version of Joshua answer, as his code works well till user doesn't perform multitouch you can tap screen with two fingers and function will be triggered two times, 4 fingers - 4 times.

After some additional test scenarios I even triggered possibility to touch very freequently and receive function executing after each tap. I added variable named 'lockTimer' which should lock any additional touchstarts before user trigger 'touchend'. Did not work at all on iOS. Further research its seems that this is due to the element having selection and the native magnification interupts the listener.

This event listener enables a thumbnail image to be opened in a bootstrap modal, if the user holds the image for ms. It uses a responsive image class therefore showing a larger version of the image. We can calculate the time difference when the touch started and when the touch end.

If the calculated time difference exceed the touch duration then we use a function name taphold. The solutions posted here ignore the fact that the user needs to touch the screen to initiate scroll.

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We only want the long-press behavior if the user is not trying to scroll. This better solution based on Joshua, sometimes the code need to be called directly inside event some web API require user acction to trigger something for this case you can use this modification:.

Learn more. Ask Question. Asked 8 years, 10 months ago. Active 20 days ago. Viewed 54k times. Christophe Debove Christophe Debove 5, 18 18 gold badges 65 65 silver badges bronze badges. Active Oldest Votes. Joshua Joshua 3, 2 2 gold badges 23 23 silver badges 19 19 bronze badges. This would be triggered on element drag drop as well. If you want to detect a real taphold that doesn't include touchmove, you should also clear the timer on touchmove event.

Semra While not sure if this is still the case The only thing i would add to your comment is also adding a tolerance range. Edit: this other answer does that. Mistic 2 2 gold badges 10 10 silver badges 23 23 bronze badges.For close to thirty years, desktop computing experiences have centered around a keyboard and a mouse or trackpad as our main user input devices.

Over the last decade, however, smartphones and tablets have brought a new interaction paradigm: touch. With the introduction of touch-enabled Windows 8 machines, and now with the release of the awesome touch-enabled Chromebook Pixel, touch is now becoming part of the expected desktop experience. One of the biggest challenges is building experiences that work not only on touch devices and mouse devices, but also on these devices where the user will use both input methods - sometimes simultaneously!

This article will help you understand how touch capabilities are built into the browser, how you can integrate this new interface mechanism into your existing apps and how touch can play nicely with mouse input. The iPhone was the first popular platform to have dedicated touch APIs built in to the web browser.

Several other browser vendors have created similar API interfaces built to be compatible with the iOS implementation, which is now described by the "Touch Events version 1" specification. Touch events are supported by Chrome and Firefox on desktop, and by Safari on iOS and Chrome and the Android browser on Android, as well as other mobile browsers like the Blackberry browser.

All done? Many developers have built sites that statically detect whether an environment supports touch events, and then make the assumption that they only need to support touch and not mouse events. This is now a faulty assumption - instead, just because touch events are present does not mean the user is primarily using that touch input device. On my Chromebook Pixel, I frequently use the trackpad, but I also reach up and touch the screen - on the same application or page, I do whatever feels most natural at the moment.

Touch events

Pointer Events are a unification of Mouse Events and touch input, as well as other input methods such as pen input. There is work to standardize the Pointer Event model at the W3Cand in the short term, there are libraries out there like PointerEvents and Hand. For really great touch and mouse interaction, you may need to customize your user experience for mouse and touch separately, but unified event handling can make this easier in many scenarios.

In the meantime, the best advice is to support both mouse and touch interaction models. There are a lot of challenges with simultaneously supporting touch and mouse events, so this article explains those challenges and the strategies to overcome them. Additionally, some of this advice is just general "implementing touch" advice, so it may be redundant if you are already used to implementing touch in a mobile context.

The first problem is that touch interfaces typically try to emulate mouse clicks - obviously, since touch interfaces need to work on applications that have only interacted with mouse events before!

You can use this as a shortcut - because "click" events will continue to be fired, whether the user clicked with a mouse or tapped their finger on the screen. However, there are a couple of problems with this shortcut. First, you have to be careful when designing more advanced touch interactions: when the user uses a mouse it will respond via a click event, but when the user touches the screen both touch and click events will occur.

For a single click the order of events is:. If you can cancel the touch events call preventDefault inside the event handlerthen no mouse events will get generated for touch. One of the most important rules of touch handlers is:. If you have a touch device, you can check out this example - or, using Chrome, you can turn on "Emulate touch events" in Chrome Developer Tools to help you test touch interfaces on a non-touch system!

This delay is to allow the browser time to determine if the user is performing another gesture - in particular, double-tap zooming.

HTML5 for the Mobile Web: Touch Events

Obviously, this can be problematic in cases where you want to have instantaneous response to a finger touch. There is ongoing work to try to limit the scenarios in which this delay occurs automatically. The first and easiest way to avoid this delay is to "tell" the mobile browser that your page is not going to need zooming - which can be done using a fixed viewport, e. Also, for Chrome on desktop class devices that support touch, and other browsers on mobile platforms when the page has viewports that are not scalable, this delay does not apply.

Browsers typically automatically implement the appropriate interaction for touch interactions on the HTML controls - so, for example, HTML5 Range controls will just work when you use touch interactions.

This was one of the first problems I ran into when upgrading my Web Audio Playground application to work with touch - the sliders were jQueryUI-based, so they did not work with click-and-drag interactions. A pitfall I've seen a few developers fall into is having touchmove and mousemove handlers call into the same codepaths. The behavior of these events is very close, but subtly different - in particular, touch events always target the element where that touch STARTED, while mouse events target the element currently under the mouse cursor.

This is why we have mouseover and mouseout events, but there are no corresponding touchover and touchout events - only touchend.With the widespread adoption of touchscreen devices, HTML5 brings to the table, among many other things, a set of touch-based interaction events. Mouse-based events such as hover, mouse in, mouse out etc. Use cases for the touch events API include gesture recognition, multi-touch, drag and drop, and any other touch-based interfaces.

The main touch events defined in the specification are outlined in the table below. The target of the event is the element in which the touch was detected, even if the touch has moved outside this element. There are plenty of more complex examples to be found on the web already, such as the canvas fingerpaint demo by Paul Irish et al.

Here we demonstrate simply how to capture and inspect a touch event. First, some HTML. We define a touch-sensitive div to which we will attach an event listener.

We also define a div at the top where we will display the screen coordinates of the most recent touch.

javascript touch event

Next we add some JavaScript to register the event listener, and add a handler function to do something with the touch data:.

In the touchHandler function we grab the x and y coordinates of the touch, and write them to the coords div:. If you are viewing this page on a device which supports touch events, you should be able to see the screen coordinates of your touches below.

Click the area to the right to activate the live demo. Depending on your device, you should be able to see the the coordinates of your touch points. Note : this demo, and the other demos on this page, are listening for touch AND mouse events, and so they should also work on non-touch enabled devices. So now we know how to grab and display some basic touch data. There are a couple of extra things we need to do to get this working.

For now, all we need to say about canvas is that it facilitates drawing graphics in a web page without much difficulty. We also need to modify the handler function from the last example, so that we now draw on this canvas element. To do this, we need to:. Touch the image below to activate the live demo, and then touch the area below to display your touches! Canvas element not supported. A short note on coordinates and element positions.

There is a small trick — to do with coordinate frames — that was glossed over in the above example. The above example will work fine if the canvas element is the only element on the page, and it is aligned with the top left of the page. However, most of the time in your webapps the element that you are interested in will not benefit for the luxury of sitting in this top-leftmost position — more likely it will be embedded in the page some distance down and across.

That is, it will be offset by a certain amount from the left of the viewport, and a certain amount from the top of the viewport. We can call these values offsetLeft and offsetTop respectively. These values must be taken into account when we want to convert the reported touch event coordinates to usable screen coordinates. Incorporating the offset is quite simple; we use something like touch.

So how do we get the offsets? To do this, I refer to the method outlined on the Quirskmode blog.This jQuery plugin provides additional touch events that can be used when developing for mobile devices.

The events are also compatible with desktop browsers to ensure ultimate compatibility for your projects. This plugin was created by Ben Major, but I have tweaked it to be compatible with browserify, allowing you to "require" it in your app. As explained, the events are each triggered by native touch events, or alternatively by click events. The plugin automatically detects whether the user's device is touch compatible, and will use the correct native events whenever required.

It is hoped that these events will help to aid single-environment development with jQuery for mobile web app development. Simply require and run 'jquery-touch-events' after jQuery has been loaded. All of the events outlined above have been written using jQuery's event.

As a result, all of the events that are supported by this library may be handled using any of jQuery's own event-specific methods, such as bindonlive for legacy and one. Removing the event with. Method chaining: Chaining has also been preserved, so you can easily use these events in conjuction with other jQuery functions, or attach multiple events in a single, chained LOC:. Each event now features a second argument that can be passed to the specified callback function.

This argument includes some basic data relating specifically to the event, and can be accessed as a standard JavaScript object. To hook into this parameter, you should use the following code:. Given the example above, touch will now contain some basic data that can be accessed through touch.

javascript touch event

The first argument will represent the last native event that occurred the names used for these two arguments is irrelevant. Each event provides different callback data. The following shows the numerous data that are passed back to the callback function inside the second parameter:. Accessed through offset. Accessed through position. Accessed through endOffset.Learn Development at Frontend Masters.

I used to think implementing swipe gestures had to be very difficult, but I have recently found myself in a situation where I had to do it and discovered the reality is nowhere near as gloomy as I had imagined.

This article is going to take you, step by step, through the implementation with the least amount of code I could come up with. We use display: flex to make sure images go alongside each other with no spaces in between. The fact that both the. Given that not all the images have the same dimensions and aspect ratio, we have a bit of white space above and below some of them. The result can be seen below, with all the images trimmed to the same height and no empty spaces anymore:.

Alright, but now we have a horizontal scrollbar on the.

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Otherwise, we create a CSS variable --n for the number of images and we use this to make. Note that we keep the previous width declarations as fallbacks. We use this to properly position the.

Changing the --i to a different integer value greater or equal to zero, but smaller than --nbrings another image into view, as illustrated by the interactive demo below where the value of --i is controlled by a range input :. See the Pen by thebabydino thebabydino on CodePen. Note that this will only work for the mouse if we set pointer-events: none on the images.

Also, Edge needs to have touch events enabled from about:flags as this option is off by default:. Before we populate the lock and move functions, we unify the touch and click cases:. Locking on "touchstart" or "mousedown" means getting and storing the x coordinate into an initial coordinate variable x0 :. In order to see how to move our. The above is the expected result and the result we get in Chrome for a little bit of drag and Firefox. However, Edge navigates backward and forward when we drag left or right, which is something that Chrome also does on a bit more drag.

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And here it is, a very basic swipe effect in about 25 lines of JavaScript and about 25 lines of CSS:. Ugh, I guess we have to forget about Edge for now. First off, nothing happens while we drag, all the action follows the "touchend" or "mouseup" event.

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