Javascript scrollIntoView() middle alignment?

问题

Javascript .scrollIntoView(boolean) provide only two alignment option.

top
bottom

What if I want to scroll the view such that. I want to bring particular element somewhere in middle of the page?

回答1:

Use window.scrollTo() for this. Get the top of the element you want to move to, and subtract one half the window height.

Demo: http://jsfiddle.net/ThinkingStiff/MJ69d/

Element.prototype.documentOffsetTop = function () {
    return this.offsetTop + ( this.offsetParent ? this.offsetParent.documentOffsetTop() : 0 );
};

var top = document.getElementById( 'middle' ).documentOffsetTop() - ( window.innerHeight / 2 );
window.scrollTo( 0, top );

回答2:

It is possible to use getBoundingClientRect() to get all the information you need to achieve this. For example, you could do something like this:

const element = document.getElementById('middle');
const elementRect = element.getBoundingClientRect();
const absoluteElementTop = elementRect.top + window.pageYOffset;
const middle = absoluteElementTop - (window.innerHeight / 2);
window.scrollTo(0, middle);

Demo: http://jsfiddle.net/cxe73c22/

This solution is more efficient than walking up parent chain, as in the accepted answer, and doesn't involve polluting the global scope by extending prototype (generally considered bad practice in javascript).

The getBoundingClientRect() method is supported in all modern browser.

回答3:

try this :

 document.getElementById('myID').scrollIntoView({
            behavior: 'auto',
            block: 'center',
            inline: 'center'
        });

refer here for more information and options : https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView

回答4:

You can do it in two steps :

myElement.scrollIntoView(true);
var viewportH = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
window.scrollBy(0, -viewportH/2); // Adjust scrolling with a negative value here

You can add the height of the element if you want to center it globaly, and not center its top :

myElement.scrollIntoView(true);
var viewportH = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
window.scrollBy(0, (myElement.getBoundingClientRect().height-viewportH)/2);

回答5:

With JQuery I use this:

function scrollToMiddle(id) {

    var elem_position = $(id).offset().top;
    var window_height = $(window).height();
    var y = elem_position - window_height/2;

    window.scrollTo(0,y);

}

Example:

<div id="elemento1">Contenido</div>

<script>
    scrollToMiddle("#elemento1");
</script>

回答6:

Improving the answer of @Rohan Orton to work for vertical and horizontal scroll.

The Element.getBoundingClientRect() method returns the size of an element and its position relative to the viewport.

var ele = $x("//a[.='Ask Question']");
console.log( ele );

scrollIntoView( ele[0] );

function scrollIntoView( element ) {
    var innerHeight_Half = (window.innerHeight >> 1); // Int value
                        // = (window.innerHeight / 2); // Float value
    console.log('innerHeight_Half : '+ innerHeight_Half);

    var elementRect = element.getBoundingClientRect();

    window.scrollBy( (elementRect.left >> 1), elementRect.top - innerHeight_Half);
}

Using Bitwise operator right shift to get int value after dividing.

console.log( 25 / 2 ); // 12.5
console.log( 25 >> 1 ); // 12

回答7:

None of the solutions on this page work when an container other than the window/document is scrolled. The getBoundingClientRect approach fails with absolute positioned elements.

In that case we need to determine the scrollable parent first and scroll it instead of the window. Here is a solution that works in all current browser versions and should even work with IE8 and friends. The trick is to scroll the element to the top of the container, so that we know exactly where it is, and then subtract half of the screen's height.

function getScrollParent(element, includeHidden, documentObj) {
    let style = getComputedStyle(element);
    const excludeStaticParent = style.position === 'absolute';
    const overflowRegex = includeHidden ? /(auto|scroll|hidden)/ : /(auto|scroll)/;

    if (style.position === 'fixed') {
        return documentObj.body;
    }
    let parent = element.parentElement;
    while (parent) {
        style = getComputedStyle(parent);
        if (excludeStaticParent && style.position === 'static') {
            continue;
        }
        if (overflowRegex.test(style.overflow + style.overflowY + style.overflowX)) {
            return parent;
        }
        parent = parent.parentElement;
    }

    return documentObj.body;
}

function scrollIntoViewCentered(element, windowObj = window, documentObj = document) {
    const parentElement = getScrollParent(element, false, documentObj);
    const viewportHeight = windowObj.innerHeight || 0;

    element.scrollIntoView(true);
    parentElement.scrollTop = parentElement.scrollTop - viewportHeight / 2;

    // some browsers (like FireFox) sometimes bounce back after scrolling
    // re-apply before the user notices.
    window.setTimeout(() => {
        element.scrollIntoView(true);
        parentElement.scrollTop = parentElement.scrollTop - viewportHeight / 2;
    }, 0);
}

来源：https://stackoverflow.com/questions/8922107/javascript-scrollintoview-middle-alignment

标签

javascript

javascript-events

js-scrollintoview