How Can I Verify If an Element Is Visible After Page Scrolling with JavaScript?

Verifying Element Visibility After Scrolling

When loading elements dynamically through AJAX, ensuring their visibility can be challenging, especially if they only become visible after scrolling the page. This article explores methods to determine whether an element is within the visible portion of the page after scrolling.

Solution: JavaScript Visibility Check

To verify element visibility, JavaScript code can be employed. Here's a function that accomplishes this:

function isScrolledIntoView(elem) {
    var docViewTop = $(window).scrollTop();
    var docViewBottom = docViewTop + $(window).height();

    var elemTop = $(elem).offset().top;
    var elemBottom = elemTop + $(elem).height();

    return ((elemBottom <= docViewBottom) && (elemTop >= docViewTop));
}

This function takes an element as input and returns a Boolean indicating whether it is visible.

Enhanced Utility Function

For a more versatile approach, consider the following utility function:

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));
        }
    }
};

This function accepts two parameters: an element and an optional flag indicating whether the element should be fully or partially visible.

Usage

To use the function, simply create an instance of the Utils class and call the isElementInView method with the desired element and optional flag:

var Utils = new Utils();
var isElementInView = Utils.isElementInView($('#flyout-left-container'), false);

if (isElementInView) {
    console.log('in view');
} else {
    console.log('out of view');
}

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