detecting true border, padding and margin from Javascript

Is there a way to detect the true border, padding and margin of elements from Javascript code? If you look at the following code:

<html>
    <head>
        <style>
        <!--
        .some_class {
            padding-left: 2px;
            border: 2px solid green;
        }   
        -->
        </style>
        <script>
        <!--
        function showDetails()
        {
            var elem = document.getElementById("my_div");
            alert("elem.className=" + elem.className);
            alert("elem.style.padding=" + elem.style.padding);
            alert("elem.style.paddingLeft=" + elem.style.paddingLeft);
            alert("elem.style.margin=" + elem.style.margin);
            alert("elem.style.marginLeft=" + elem.style.marginLeft);
            alert("elem.style.border=" + elem.style.border);
            alert("elem.style.borderLeft=" + elem.style.borderLeft);
        }
        -->
        </script>
    </head>
    <body>
        <div id="my_div" class="some_class" style="width: 300px; height: 300px; margin-left: 4px;">
            some text here
        </div>
        <button onclick="showDetails();">show details</button>
    </body>
</html>

you can see, if you click the button, that the padding is not reported right. Only the properties defined directly through "style" are reported back, those defined through a CSS class are not reported.

Is there a way to get back the final values of these properties? I mean the values obtained after all CSS settings are computed and applied by the browser.

Answers:

Answer

It's possible, but of course, every browser has its own implementation. Luckily, PPK has done all the hard work for us:

http://www.quirksmode.org/dom/getstyles.html

Answer

the style property can get the styles that are assigned inline like

<div id="target" style="color:#ddd;margin:10px">test</div> if you want to get the styles assigned in outer css file or <style/> element, try this:

var div = document.getElementById("target");
var style = div.currentStyle || window.getComputedStyle(div);
display("Current marginTop: " + style.marginTop);

if you are using jQuery, @vsync 's solution is fine.

Answer

With jQuery:

var $elm = $('.box');
var hPadding = $elm.outerWidth() - $elm.width();
var vPadding = $elm.outerHeight() - $elm.height();
var hBorder = $elm.outerWidth() - $elm.innerWidth();
var vBorder = $elm.outerHeight() - $elm.innerHeight();

console.log("Horizontal padding & border: ", hPadding);
console.log("Vertical padding & border: ", vPadding);
console.log("Horizontal border: ", hBorder);
console.log("Vertical border: ", vBorder);
.box{ 
  width: 50%;
  padding:10vw; 
  border:10px solid red; 
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class='box'></div>

Your way (but you have to state paddingLeft, paddingRight..not just 'padding' ):

var elm = $('.box');
console.log("padding left (PX): ", elm.css("paddingLeft"));
.box { 
  padding:0 50px 0 5vw; 
  border: 2px solid green; 
  width: 300px; 
  height: 300px; 
  margin-left: 4px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="box">some text here</div>

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