找到一篇讲解offsetHeight, clientHeight, scrollHeight三者区别的文章,摘要出重点记录一下:
returns the inner height of an element in pixels, including padding but not the horizontal scrollbar height, border, or margin
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.
is a measurement of the height of an element's content including content not visible on the screen due to overflow
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.

例子代码:
js
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 +