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.

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

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.

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>

来源：https://stackoverflow.com/questions/349257/detecting-true-border-padding-and-margin-from-javascript

标签

javascript

css

border

padding

margin