Check if element is visible after scrolling

I'm loading elements via AJAX. Some of them are only visible if you scroll down the page.
Is there any way I can know if an element is now in the visible part of the page?

---

This should do the trick:

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));
}

Simple Utility Function This will allow you to call a utility function that accepts the element you're looking for and if you want the element to be fully in view or partially.

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();

Usage

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

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

---

Vanilla的这个答案：

function isScrolledIntoView(el) {
    var rect = el.getBoundingClientRect();
    var elemTop = rect.top;
    var elemBottom = rect.bottom;

    // Only completely visible elements return true:
    var isVisible = (elemTop >= 0) && (elemBottom <= window.innerHeight);
    // Partially visible elements return true:
    //isVisible = elemTop < window.innerHeight && elemBottom >= 0;
    return isVisible;
}

---

The best method I have found so far is the jQuery appear plugin. Works like a charm.

Mimics a custom "appear" event, which fires when an element scrolls into view or otherwise becomes visible to the user.

$('#foo').appear(function() {
  $(this).text('Hello world');
});

This plugin can be used to prevent unnecessary requests for content that's hidden or outside the viewable area.

链接地址: http://www.djcxy.com/p/2362.html

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