shibualexis shibualexis - 7 months ago 12
HTML Question

What is offsetHeight, clientHeight, scrollHeight?

Thought of explaining what is the difference between

offsetHeight
,
clientHeight
and
scrollHeight
or
offsetWidth
,
clientWidth
and
scrollWidth
?

One must know this difference before working on the client side. Otherwise half of their life will be spent in fixing the UI.

Fiddle, or inline below:



function whatis(propType) {
var mainDiv = document.getElementById("MainDIV");
if (window.sampleDiv == null) {
var div = document.createElement("div");
window.sampleDiv = div;
}
div = window.sampleDiv;
var propTypeWidth = propType.toLowerCase() + "Width";
var propTypeHeight = propType + "Height";

var computedStyle = window.getComputedStyle(mainDiv, null);
var borderLeftWidth = computedStyle.getPropertyValue("border-left-width");
var borderTopWidth = computedStyle.getPropertyValue("border-top-width");

div.style.position = "absolute";
div.style.left = mainDiv.offsetLeft + Math.round(parseFloat((propType == "client") ? borderLeftWidth : 0)) + "px";
div.style.top = mainDiv.offsetTop + Math.round(parseFloat((propType == "client") ? borderTopWidth : 0)) + "px";
div.style.height = mainDiv[propTypeHeight] + "px";
div.style.lineHeight = mainDiv[propTypeHeight] + "px";
div.style.width = mainDiv[propTypeWidth] + "px";
div.style.textAlign = "center";
div.innerHTML = propTypeWidth + " X " + propTypeHeight + "( " +
mainDiv[propTypeWidth] + " x " + mainDiv[propTypeHeight] + " )";



div.style.background = "rgba(0,0,255,0.5)";
document.body.appendChild(div);

}
document.getElementById("offset").onclick = function() {
whatis('offset');
}
document.getElementById("client").onclick = function() {
whatis('client');
}
document.getElementById("scroll").onclick = function() {
whatis('scroll');
}

#MainDIV {
border: 5px solid red;
}

<button id="offset">offsetHeight & offsetWidth</button>
<button id="client">clientHeight & clientWidth</button>
<button id="scroll">scrollHeight & scrollWidth</button>

<div id="MainDIV" style="margin:auto; height:200px; width:400px; overflow:auto;">
<div style="height:400px; width:500px; overflow:hidden;">

</div>
</div>




Answer

To know the difference you have to understand the box model, but basically:

clientHeight:

returns the inner height of an element in pixels, including padding but not the horizontal scrollbar height, border, or margin

offsetHeight:

is a measurement which includes the element borders, the element vertical padding, the element horizontal scrollbar (if present, if rendered) and the element CSS height.

scrollHeight:

is a measurement of the height of an element's content including content not visible on the screen due to overflow


I will make it easier:

Consider:

<element>                                     
    <!-- *content*: child nodes: -->        | content
    A child node as text node               | of
    <div id="another_child_node"></div>     | the
    ... and I am the 4th child node         | element
</element>                                    

scrollHeight: ENTIRE content & padding (visible or not)
Height of all content + paddings, despite of height of the element.

clientHeight: VISIBLE content & padding
Only visible height: content portion limited by explicitly defined height of the element.

offsetHeight: VISIBLE content & padding + border + scrollbar
Height occupied by the element on document.

scrollHeight clientHeight and offsetHeight

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