Preventing Page from Scrolling on Focus Switching

Disable scrolling when changing focus form elements ipad web app

I've found that in UIWebView, document.body is also sometimes moved. So I use:

    input.onfocus = function () {
        window.scrollTo(0, 0);
        document.body.scrollTop = 0;
    }

How to programmatically disable page scrolling with jQuery

The only way I've found to do this is similar to what you described:

1. Grab current scroll position (don't forget horizontal axis!).
2. Set overflow to hidden (probably want to retain previous overflow value).
3. Scroll document to stored scroll position with scrollTo().

Then when you're ready to allow scrolling again, undo all that.

Edit: no reason I can't give you the code since I went to the trouble to dig it up...

// lock scroll position, but retain settings for later
var scrollPosition = [
  self.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft,
  self.pageYOffset || document.documentElement.scrollTop  || document.body.scrollTop
];
var html = jQuery('html'); // it would make more sense to apply this to body, but IE7 won't have that
html.data('scroll-position', scrollPosition);
html.data('previous-overflow', html.css('overflow'));
html.css('overflow', 'hidden');
window.scrollTo(scrollPosition[0], scrollPosition[1]);


// un-lock scroll position
var html = jQuery('html');
var scrollPosition = html.data('scroll-position');
html.css('overflow', html.data('previous-overflow'));
window.scrollTo(scrollPosition[0], scrollPosition[1])

Is it possible to avoid page scrolling when changing focus on HTML elements? (Using JavaScript)

You can simply add prevent default:

function tabnav(event){
  event.preventDefault();
  .

Of course insert it into the 'case arrow down/up' otherwise you won't have any input at all

How do I stop a web page from scrolling to the top when a link is clicked that triggers JavaScript?

You need to prevent the default action for the click event (i.e. navigating to the link target) from occurring.

There are two ways to do this.

Option 1: event.preventDefault()

Call the .preventDefault() method of the event object passed to your handler. If you're using jQuery to bind your handlers, that event will be an instance of jQuery.Event and it will be the jQuery version of .preventDefault(). If you're using addEventListener to bind your handlers, it will be an Event and the raw DOM version of .preventDefault(). Either way will do what you need.

Examples:

$('#ma_link').click(function($e) {
    $e.preventDefault();
    doSomething();
});

document.getElementById('#ma_link').addEventListener('click', function (e) {
    e.preventDefault();
    doSomething();
})

Option 2: return false;

In jQuery:

Returning false from an event handler will automatically call event.stopPropagation() and event.preventDefault()

So, with jQuery, you can alternatively use this approach to prevent the default link behaviour:

$('#ma_link').click(function(e) {
     doSomething();
     return false;
});

If you're using raw DOM events, this will also work on modern browsers, since the HTML 5 spec dictates this behaviour. However, older versions of the spec did not, so if you need maximum compatibility with older browsers, you should call .preventDefault() explicitly. See event.preventDefault() vs. return false (no jQuery) for the spec detail.

Prevent body scrolling but allow overlay scrolling

Theory

Looking at current implementation of the pinterest site (it might change in the future), when you open the overlay a noscroll class is applied to the body element and overflow: hidden is set, thus body is no longer scrollable.

The overlay (created on-the-fly or already inside the page and made visible via display: block, it makes no difference) has position : fixed and overflow-y: scroll, with top, left, right and bottom properties set to 0: this style makes the overlay fill the whole viewport.

The div inside the overlay is instead just in position: static then the vertical scrollbar you see is related to that element. As a result the content is scrollable but overlay remains fixed.

When you close the zoom you hide the overlay (via display: none) and then you could also entirely remove it via javascript (or just the content inside, it's up to you how to inject it).

As a final step you have to also remove the noscroll class to the body (so the overflow property returns to its initial value)

---

Code

Codepen Example

(it works by changing the aria-hidden attribute of the overlay in order to show and hide it and to increase its accessibility).

Markup

(open button)

<button type="button" class="open-overlay">OPEN LAYER</button>

(overlay and close button)

<section class="overlay" aria-hidden="true">
  <div>
    <h2>Hello, I'm the overlayer</h2>
    ...   
    <button type="button" class="close-overlay">CLOSE LAYER</button>
  </div>
</section>

CSS

.noscroll { 
  overflow: hidden;
}

.overlay { 
   position: fixed; 
   overflow-y: scroll;
   top: 0; right: 0; bottom: 0; left: 0; }

[aria-hidden="true"]  { display: none; }
[aria-hidden="false"] { display: block; }

Javascript (vanilla-JS)

var body = document.body,
    overlay = document.querySelector('.overlay'),
    overlayBtts = document.querySelectorAll('button[class$="overlay"]');

[].forEach.call(overlayBtts, function(btt) {

  btt.addEventListener('click', function() { 

     /* Detect the button class name */
     var overlayOpen = this.className === 'open-overlay';

     /* Toggle the aria-hidden state on the overlay and the 
        no-scroll class on the body */
     overlay.setAttribute('aria-hidden', !overlayOpen);
     body.classList.toggle('noscroll', overlayOpen);

     /* On some mobile browser when the overlay was previously
        opened and scrolled, if you open it again it doesn't 
        reset its scrollTop property */
     overlay.scrollTop = 0;

  }, false);

});

---

Finally, here's another example in which the overlay opens with a fade-in effect by a CSS transition applied to the opacity property. Also a padding-right is applied to avoid a reflow on the underlying text when the scrollbar disappears.

Codepen Example (fade)

CSS

.noscroll { overflow: hidden; }

@media (min-device-width: 1025px) {
    /* not strictly necessary, just an experiment for 
       this specific example and couldn't be necessary 
       at all on some browser */
    .noscroll { 
        padding-right: 15px;
    }
}

.overlay { 
     position: fixed; 
     overflow-y: scroll;
     top: 0; left: 0; right: 0; bottom: 0;
}

[aria-hidden="true"] {    
    transition: opacity 1s, z-index 0s 1s;
    width: 100vw;
    z-index: -1; 
    opacity: 0;  
}

[aria-hidden="false"] {  
    transition: opacity 1s;
    width: 100%;
    z-index: 1;  
    opacity: 1; 
}

Prevent iOS from handling focus event on an <input>

This has been quite a hack, but it seems to work:

body, html {
    margin: 0;
    overflow: auto;
    height: 100%;
    -webkit-overflow-scrolling: touch;
}

Just add this to your CSS. I needed to remove the margin, not sure if that will affect your design. If so, you might try to add padding instead, but I haven't tried.

The idea is to prevent the html element to scroll, tricking Safari as it seems that it is only attempting to do it in the outer most element.

If the html doesn't scroll, I need to add the scroll back, so I apply it to the body. That makes the scroll to lose the momentum, and to add it back you need that -webkit-overflow-scrolling: touch thing.

So, to be more clear of what is going on, the code should be like this - but I haven't tried it:

html {
    margin: 0;
    overflow: hidden;
    height: 100%
}
body {
    margin: 0;
    overflow: auto;
    height: 100%;
    -webkit-overflow-scrolling: touch;
}

---

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