在JavaScript中滚动底部

Question

I have a working bottom function in JavaScript to detect if the user scrolls at the bottom. However, a problem comes when the user has a strange resolution (like windows scale) or when you zoom. The function is not working anymore and can't detect the bottom.

Here is what I did :

    const bottom = e.target.scrollHeight - e.target.scrollTop === e.target.clientHeight;

    if (bottom) {
        this.props.getNewValues();
    }

Is there a way to avoid that? Even when you don't zoom, this is not working for people displaying the site on a TV or something like this (like a friend of mine did)

Thanks you

EDIT : I'm applying this on a precise element and I repeat that my solution is working except by unzooming. Unzooming provides float values that made the response not really accurate (it goes from 1 to 50px of difference based on the zoom made)

Answer 1

I use this function (can't take credit as someone else wrote it - sorry for no credit - it was ages ago). Maybe you can adapt this to your use case:

(function($) {

    //CHECK SCROLLED INTO VIEW UTIL
    function Utils() {

    }

    Utils.prototype = {
        constructor: Utils,
        isElementInView: function (element, fullyInView) {
            var pageTop = $(window).scrollTop();
            var pageBottom = pageTop + $(window).height();
            var elementTop = $(element).offset().top;
            var elementBottom = elementTop + $(element).height();

            if (fullyInView === true) {
                return ((pageTop < elementTop) && (pageBottom > elementBottom));
            } else {
                return ((elementTop <= pageBottom) && (elementBottom >= pageTop));
            }
        }
    };

    var Utils = new Utils();
    //END CHECK SCROLLED INTO VIEW UTIL

    //USING THE ELEMENT IN VIEW UTIL
    //this function tells what to do do when the element is or isnt in view.
    //var inView = Utils.isElementInView(el, false); Where FALSE means the element doesnt need to be completely in view / TRUE would mean the element needs to be completely in view
    function IsEInView(el) {

        var inView = Utils.isElementInView(el, false);

        if(inView) {

            //console.log('in view');

        } else {
            //console.log('not in view');
        }

    };

    //Check to make sure the element you want to be sure is visible is present on the page
    var variableOfYourElement = $('#variableOfYourElement');

    //if it is on this page run the function that checks to see if it is partially or fully in view
    if( variableOfYourElement.length ) {

        //run function on page load
        IsEInView(variableOfYourElement);

        //run function if the element scrolls into view
        $(window).scroll(function(){

            IsEInView(variableOfYourElement);

        });

    }
    //END USING THE ELEMENT IN VIEW UTIL

})(jQuery);