Code for finding the relative position of a child element in the parent element in Javascript

I tried it all night and found a method.
My head is still confused. Write it down first and analyze it later. CopyCodeThe Code is as follows: // locate the relative position of the child element in the parent Element
Function getelementtop (element ){
VaR El = (typeof element = "string ")? Document. getelementbyid (element): element;
If (El. parentnode = NULL | El. style. Display = 'None '){
Return false;
}
Return El. offsettop-El. parentnode. offsettop;
}

This function can obtain the relative height of the child element in the parent element. you can locate the position of the child element by setting the scrolltop attribute of the parent element.