Determine if an element in an iframe is visible on

2019-02-07 02:54发布

站内问答 / JavaScript
1456 1 4

I need to determine if an element in an iframe is visible on the screen. (if it is on the visible part of the screen) I mean the page can be very long and user must scroll to see the element

index.html:

<html>
...
...
<iframe src="iframe.html" />
...
...
</html>

iframe.html:

<html>
...
...
<div id="element"></div>
....
...
<script type="text/javascript">
    var el = document.getElementById('element');
    if (isElementVisible(el)) {
      // do something
    }
</script>
</html>

How to write such a function isElementVisible()?

1条回答
何必那么认真
2楼-- · 2019-02-07 03:19

Here is an example of what you are trying to achieve.

Working example

Just the iframe

Basically, this is the function that should go inside your iframe:

function isElementVisible(element)
{
    var elementPosition = element.offset().top;
    var currentScroll = window.parent.$("iframe").contents().scrollTop();
    var screenHeight = window.parent.$("iframe").height();
    var visibleArea = currentScroll + screenHeight;
    return (elementPosition < visibleArea);
}

Trigger your checks with a scroll event handler.

$(window).scroll(function(){
if( isElementVisible( element ) )
   // Perform your code.
});

This works assuming the iframe is in the same domain as the parent frame. I use jQuery for convenience.

查看更多
0人赞 添加讨论(0) 举报
登录 后发表回答
相关问题
查看全部
相关文章
查看全部
收藏的人(4)