How to remove/ignore :hover css style on touch dev

问题:

I want to ignore all :hover CSS declarations if a user visits our website via touch device. Because the :hover CSS does not make sense, and it can even be disturbing if a tablet triggers it on click/tap because then it might stick until the element loses focus. To be honest, I don't know why touch devices feel the need to trigger :hover in first place - but this is reality, so this problem is reality as well.

a:hover {
   color:blue;
   border-color:green;
   // etc. > ignore all at once for touch devices
}

So, (how) can I remove/ignore all CSS :hover declarations at once (without having to know each one) for touch devices after having them declared?

回答1:

There are multiple solutions for this issue.

Quick'n'dirty - remove :hover styles using JS

You can remove all the CSS rules containing :hover using Javascript. This has the advantage of not having to touch CSS and being compatible even with older browsers.

function hasTouch() {
    return 'ontouchstart' in document.documentElement
           || navigator.maxTouchPoints > 0
           || navigator.msMaxTouchPoints > 0;
}

if (hasTouch()) { // remove all :hover stylesheets
    try { // prevent exception on browsers not supporting DOM styleSheets properly
        for (var si in document.styleSheets) {
            var styleSheet = document.styleSheets[si];
            if (!styleSheet.rules) continue;

            for (var ri = styleSheet.rules.length - 1; ri >= 0; ri--) {
                if (!styleSheet.rules[ri].selectorText) continue;

                if (styleSheet.rules[ri].selectorText.match(':hover')) {
                    styleSheet.deleteRule(ri);
                }
            }
        }
    } catch (ex) {}
}

Limitations: stylesheets must be hosted on the same domain (that means no CDNs). Disables hovers on mixed mouse & touch devices like Surface, which hurts the UX.

CSS-only - use media queries

Place all your :hover rules in a @media block:

@media (hover: hover) {
    a:hover { color: blue; }
}

or alternatively, override all your hover rules (compatible with older browsers):

a:hover { color: blue; }

@media (hover: none) {
    a:hover { color: inherit; }
}

Limitations: works only on iOS 9.0+, Chrome for Android or Android 5.0+ when using WebView. hover: hover breaks hover effects on older browsers, hover: none needs overriding all the previously defined CSS rules. Both are incompatible with mixed mouse & touch devices.

The most robust - use special CSS class and detect touch via JS

This method needs prepending all the hover rules with body.hasHover. (or a class name of your choice)

body.hasHover a:hover { color: blue; }

The hasHover class may be added using hasTouch() from the first example:

if (!hasTouch()) {
    document.body.className += ' hasHover';
}

However, this has the same issue with mixed touch devices as previous examples, which brings us to the ultimate solution. Enable hover effects whenever a mouse cursor is moved, disable hover effects whenever a touch is detected.

function watchForHover() {
    var hasHoverClass = false;
    var container = document.body;
    var lastTouchTime = 0;

    function enableHover() {
        // filter emulated events coming from touch events
        if (new Date() - lastTouchTime < 500) return;
        if (hasHoverClass) return;

        container.className += ' hasHover';
        hasHoverClass = true;
    }

    function disableHover() {
        if (!hasHoverClass) return;

        container.className = container.className.replace(' hasHover', '');
        hasHoverClass = false;
    }

    function updateLastTouchTime() {
        lastTouchTime = new Date();
    }

    document.addEventListener('touchstart', updateLastTouchTime, true);
    document.addEventListener('touchstart', disableHover, true);
    document.addEventListener('mousemove', enableHover, true);

    enableHover();
}

watchForHover();

This should work basically in any browser and enables/disables hover styles as needed. Try it here: https://jsfiddle.net/dkz17jc5/19/

回答2:

Pointer adaptation to the rescue!

Since this hasn't been touched in awhile, you can use:

a:link {
   color: red;
}

a:hover {
   color:blue;
}

@media (hover: none) {
   a:link {
      color: red;
   }
}

See this demo in both your desktop browser and your phone browser. Supported by modern touch devices.

Note: Keep in mind that since a Surface PC's primary input (capability) is a mouse, it will end up being a blue link, even if it's a detached (tablet) screen. Browsers will (should) always default to the most precise input's capability.

回答3:

I'm dealing with a similar problem currently.

There are two main options that occur to me immediately: (1) user-string checking, or (2) maintaining separate mobile pages using a different URL and having users choose what's better for them.

1. If you're able to use an internet duct-tape language such as PHP or Ruby, you can check the user string of the device requesting a page, and simply serve the same content but with a <link rel="mobile.css" /> instead of the normal style.

User strings have identifying information about browser, renderer, operating system, etc. It would be up to you to decide what devices are "touch" versus non-touch. You may be able to find this information available somewhere and map it into your system.

A. If you're allowed to ignore old browsers, you just have to add a single rule to the normal, non-mobile css, namely: EDIT: Erk. After doing some experimentation, I discovered the below rule also disables the ability to follow links in webkit-browsers in addition to just causing aesthetic effects to be disabled - see http://jsfiddle.net/3nkcdeao/
As such, you'll have to be a bit more selective as to how you modify rules for the mobile case than what I show here, but it may be a helpful starting point:

* { 
    pointer-events: none !important; /* only use !important if you have to */
}

As a sidenote, disabling pointer-events on a parent and then explicitly enabling them on a child currently causes any hover-effects on the parent to become active again if a child-element enters :hover.
See http://jsfiddle.net/38Lookhp/5/

B. If you're supporting legacy web-renderers, you'll have to do a bit more work along the lines of removing any rules which set special styles during :hover. To save everyone time, you might just want to build an automated copying + seding command which you run on your standard style sheets to create the mobile versions. That would allow you to just write/update the standard code and scrub away any style-rules which use :hover for the mobile version of your pages.

2. (I) Alternatively, simply make your users aware that you have an m.website.com for mobile devices in addition to your website.com. Though subdomaining is the most common way, you could also have some other predictable modification of a given URL to allow mobile users to access the modified pages. At that stage, you would want to be sure they don't have to modify the URL every time they navigate to another part of the site.

Again here, you may be able to just add an extra rule or two to the stylesheets or be forced to do something slightly more complicated using sed or a similar utility. It would probably be easiest to apply :not to your styling rules like div:not(.disruptive):hover {... wherein you would add class="disruptive" to elements doing annoying things for mobile users using js or the server language, instead of munging the CSS.

2. (II) You can actually combine the first two and (if you suspect a user has wandered to the wrong version of a page) you can suggest that they switch into/out of the mobile-type display, or simply have a link somewhere which allows users to flop back and forth. As already-stated, @media queries might also be something to look use in determining what's being used to visit.

3. (III) If you're up for a jQuery solution once you know what devices are "touch" and which aren't, you might find CSS hover not being ignored on touch-screen devices helpful.

回答4:

try this:

@media (hover:<s>on-demand</s>) {
    button:hover {
        background-color: #color-when-NOT-touch-device;
    }
}

UPDATE: unfortunately W3C has removed this property from the specs (https://github.com/w3c/csswg-drafts/commit/2078b46218f7462735bb0b5107c9a3e84fb4c4b1).

回答5:

I have encountered the same problem (in my case with Samsung mobile browsers) and therefore I stumbled upon this question.

Thanks to Calsal's answer I found something that I believe will exclude virtually all desktop browsers because it seems to be recognized by the mobile browsers I tried (see screenshot from a compiled table: CSS pointer feature detection table ).

MDN web docs state that

The pointer CSS @media feature can be used to apply styles based on whether the user's primary input mechanism is a pointing device, and if so, how accurate it is

.

What I discovered is that pointer: coarse is something that is unknown to all desktop browsers in the attached table but known to all mobile browsers in the same table. This seems to be most effective choice because all other pointer keyword values give inconsistent results.

Hence you could construct a media query like Calsal described but slightly modified. It makes use of a reversed logic to rule out all touch devices.

Sass mixin:

@mixin hover-supported {    
    /* 
     * https://developer.mozilla.org/en-US/docs/Web/CSS/@media/pointer 
     * coarse: The primary input mechanism includes a pointing device of limited accuracy.
     */
    @media not all and (pointer: coarse) {
        &:hover {
            @content;
        }
    }
}

a {
    color:green;
    border-color:blue;

    @include hover-supported() {
        color:blue;
        border-color:green;
    }
}

Compiled CSS:

a {
  color: green;
  border-color: blue;
}
@media not all and (pointer: coarse) {
  a:hover {
    color: blue;
    border-color: green;
  }
}

It is also described in this gist I created after researching the problem. Codepen for empirical research.

UPDATE: As of writing this update, 2018-08-23, and pointed out by @DmitriPavlutin this technique no longer seems to work with Firefox desktop.

回答6:

You can use Modernizr JS (see also this StackOverflow answer), or make a custom JS function:

function is_touch_device() {
 return 'ontouchstart' in window        // works on most browsers 
  || navigator.maxTouchPoints;       // works on IE10/11 and Surface
};

if ( is_touch_device() ) {
  $('html').addClass('touch');
} else {
  $('html').addClass('no-touch');
} 

to detect the support of touch event in the browser, and then assign a regular CSS property, traversing the element with the html.no-touch class, like this:

html.touch a {
    width: 480px;
}

/* FOR THE DESKTOP, SET THE HOVER STATE */
html.no-touch a:hover {
   width: auto;
   color:blue;
   border-color:green;
}

回答7:

This is also a possible workaround, but you will have to go through your css and add a .no-touch class before your hover styles.

Javascript:

if (!("ontouchstart" in document.documentElement)) {
document.documentElement.className += " no-touch";
}

CSS Example:

<style>
p span {
    display: none;
}

.no-touch p:hover span {
    display: inline;
}
</style>
<p><a href="/">Tap me</a><span>You tapped!</span></p>

Source

P.s. But we should remember, there are coming more and more touch-devices to the market, which are also supporting mouse input at the same time.

回答8:

This might not be a perfect solution yet (and it’s with jQuery) but maybe it’s a direction / concept to work on: what about doing it the other way round? Which means deactivating the :hover css states by default and activate them if a mousemove event is detected anywhere on the document. Of course this does not work if someone deactivated js. What else might speak against doing it this way round?

Maybe like this:

CSS:

/* will only work if html has class "mousedetected" */
html.mousedetected a:hover {
   color:blue;
   border-color:green;
}

jQuery:

/* adds "mousedetected" class to html element if mouse moves (which should never happen on touch-only devices shouldn’t it?) */
$("body").mousemove( function() {
    $("html").addClass("mousedetected");
});

回答9:

According to Jason´s answer we can address only devices that doesn't support hover with pure css media queries. We can also address only devices that support hover, like moogal´s answer in a similar question, with @media not all and (hover: none). It looks weird but it works.

I made a Sass mixin out of this for easier use:

@mixin hover-supported {
    @media not all and (hover: none) {
        &:hover {
            @content;
        }
    }
}

The following would change background-color of .container from red to blue on hover for devices that support it and remain red for touch devices:

.container {
    background-color: red;

    @include hover-supported() {
        background-color: blue;
    }
}

回答10:

It was helpful for me: link

function hoverTouchUnstick() {
    // Check if the device supports touch events
    if('ontouchstart' in document.documentElement) {
        // Loop through each stylesheet
        for(var sheetI = document.styleSheets.length - 1; sheetI >= 0; sheetI--) {
            var sheet = document.styleSheets[sheetI];
            // Verify if cssRules exists in sheet
            if(sheet.cssRules) {
                // Loop through each rule in sheet
                for(var ruleI = sheet.cssRules.length - 1; ruleI >= 0; ruleI--) {
                    var rule = sheet.cssRules[ruleI];
                    // Verify rule has selector text
                    if(rule.selectorText) {
                        // Replace hover psuedo-class with active psuedo-class
                        rule.selectorText = rule.selectorText.replace(":hover", ":active");
                    }
                }
            }
        }
    }
}

回答11:

Try this easy 2019 jquery solution, although its been around a while;

1. add this plugin to head:

   src="https://code.jquery.com/ui/1.12.0/jquery-ui.min.js"

2. add this to js:

   $("*").on("touchend", function(e) { $(this).focus(); }); //applies to all elements

3. some suggested variations to this are:

   $(":input, :checkbox,").on("touchend", function(e) {(this).focus);}); //specify elements

   $("*").on("click, touchend", function(e) { $(this).focus(); }); //include click event

   css: body { cursor: pointer; } //touch anywhere to end a focus

Notes

• place plugin before bootstrap.js to avoif affecting tooltips
• only tested on iphone XR ios 12.1.12, and ipad 3 ios 9.3.5, using Safari or Chrome.

References:

https://code.jquery.com/ui/

https://api.jquery.com/category/selectors/jquery-selector-extensions/

回答12:

This can be solved with sass/scss and a media query with the desired breakpoint.

.myclass {
    background-color: blue;
    &:hover {
        @media screen and (max-width: 320px) {
            background-color: red;
        }
    }
}