Detailed explanation of jQuery's position() method

Detailed explanation of jQuery's position() method_jquery

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Release： 2016-05-16 15:49:39

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Definition and usage of position() method:

This method gets the offset of the matched element relative to some element.

The returned object contains an object with two integer attributes (top and left).

This method only works on visible elements.

Grammar structure:

$(selector).position()

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At the beginning of the tutorial, the reason why it is said is to get the offset of the matching element relative to some elements. Many tutorials say that the offset returned by the method is relative to the parent element, but this is not entirely true. This method will process the matching element with absolute positioning. Of course, it does not mean that the matching element is actually set to absolute positioning. The offset reference principle of the method is as follows:

1. If the parent element does not use positioning (the position attribute value is relative, absolute or fixed), then the offset reference object is the window.

2. If any of the parent elements uses positioning, then the reference object of the offset is the nearest element that uses positioning,

Example code:

<!DOCTYPE html>
<html>
<head>
<meta charset=" utf-8">
<style type="text/css">
*{
 margin:0px;
 padding:0px;
}
.father{
 background-color:green;
 width:200px;
 height:200px;
 padding:50px;
 margin-bottom:50px;
 margin-left:100px;
}
.children{
 height:150px;
 width:150px;
 background-color:red;
 line-height:150px;
 text-align:center;
}
</style>
<script type="text/javascript" src="mytest/jQuery/jquery-1.8.3.js"></script>
<script type="text/javascript">
$(document).ready(function(){
 $(".children").each(function(){
  var text;
  text="left:"+$(this).position().left;
  text+="top:"+$(this).position().top;
  $(this).text(text);
 })
})
</script>
</head>
<body>
<div class="father" style="position:relative">
 <div class="children"></div>
</div>
<div class="father">
 <div class="children"></div>
</div>
</body>
</html>

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In the top combination in the above code, since the parent element uses relative positioning, the obtained offset is relative to the parent element. In the bottom combination, since the parent element does not use positioning, the offset reference object is the window.

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