How do you get the real-time distance of a child element from the parent element or body?

  node.js, question

I started to choose offsetop but found that the value of OffsetOp was not changed when the position of child elements was dynamically adjusted?

Some codes are as follows:
 var inde_arr = document.getElementsByClassName('inde'),
 fir_li = li_arr[1].offsetTop;
 I slide the li label of the list through iscroll.js, but the offsetTop of the li label in the list will not change. Solve?

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