我有下面的样本html，有一个DIV有100%的宽度。它包含了一些元素。在执行窗口调整大小时，内部元素可能会被重新定位，div的尺寸可能会改变。我在问是否有可能挂钩div的维度变化事件?以及如何做到这一点?我目前绑定回调函数到目标DIV上的jQuery调整大小事件，但是，没有输出控制台日志，如下所示:
<html>
<head>
<script type="text/javascript" language="javascript" src="http://code.jquery.com/jquery-1.6.1.min.js"></script>
<script type="text/javascript" language="javascript">
$('#test_div').bind('resize', function(){
console.log('resized');
});
</script>
</head>
<body>
<div id="test_div" style="width: 100%; min-height: 30px; border: 1px dashed pink;">
<input type="button" value="button 1" />
<input type="button" value="button 2" />
<input type="button" value="button 3" />
</div>
</body>
</html>
我不建议使用setTimeout()，因为它会降低性能!
相反，你可以使用DOM ResizeObserver方法来监听Div大小的变化。
const myObserver = new ResizeObserver(entries => {
// this will get called whenever div dimension changes
entries.forEach(entry => {
console.log('width', entry.contentRect.width);
console.log('height', entry.contentRect.height);
});
});
const someEl = document.querySelector('.some-element');
// start listening to changes
myObserver.observe(someEl);
// later, stop listening to changes
myObserver.disconnect();
使用MutationObserver的旧答案:
用于监听HTML元素属性、子树和类的更改:
JS:
var observer = new MutationObserver(function(mutations) {
console.log('size changed!');
});
var target = document.querySelector('.mydiv');
observer.observe(target, {
attributes: true,
childList: true,
subtree: true
});
HTML:
<div class='mydiv'>
</div>
这是小提琴。试着改变div大小。
您可以将您的方法进一步封装在debounce方法中以提高效率。debounce将每x毫秒触发一次你的方法，而不是在DIV被调整大小的每一毫秒触发一次。
ResizeSensor.js是一个巨大库的一部分，但我把它的功能简化为:
function ResizeSensor(element, callback)
{
let zIndex = parseInt(getComputedStyle(element));
if(isNaN(zIndex)) { zIndex = 0; };
zIndex--;
let expand = document.createElement('div');
expand.style.position = "absolute";
expand.style.left = "0px";
expand.style.top = "0px";
expand.style.right = "0px";
expand.style.bottom = "0px";
expand.style.overflow = "hidden";
expand.style.zIndex = zIndex;
expand.style.visibility = "hidden";
let expandChild = document.createElement('div');
expandChild.style.position = "absolute";
expandChild.style.left = "0px";
expandChild.style.top = "0px";
expandChild.style.width = "10000000px";
expandChild.style.height = "10000000px";
expand.appendChild(expandChild);
let shrink = document.createElement('div');
shrink.style.position = "absolute";
shrink.style.left = "0px";
shrink.style.top = "0px";
shrink.style.right = "0px";
shrink.style.bottom = "0px";
shrink.style.overflow = "hidden";
shrink.style.zIndex = zIndex;
shrink.style.visibility = "hidden";
let shrinkChild = document.createElement('div');
shrinkChild.style.position = "absolute";
shrinkChild.style.left = "0px";
shrinkChild.style.top = "0px";
shrinkChild.style.width = "200%";
shrinkChild.style.height = "200%";
shrink.appendChild(shrinkChild);
element.appendChild(expand);
element.appendChild(shrink);
function setScroll()
{
expand.scrollLeft = 10000000;
expand.scrollTop = 10000000;
shrink.scrollLeft = 10000000;
shrink.scrollTop = 10000000;
};
setScroll();
let size = element.getBoundingClientRect();
let currentWidth = size.width;
let currentHeight = size.height;
let onScroll = function()
{
let size = element.getBoundingClientRect();
let newWidth = size.width;
let newHeight = size.height;
if(newWidth != currentWidth || newHeight != currentHeight)
{
currentWidth = newWidth;
currentHeight = newHeight;
callback();
}
setScroll();
};
expand.addEventListener('scroll', onScroll);
shrink.addEventListener('scroll', onScroll);
};
如何使用:
let container = document.querySelector(".container");
new ResizeSensor(container, function()
{
console.log("dimension changed:", container.clientWidth, container.clientHeight);
});
这篇博文帮助我有效地检测DOM元素的大小变化。
http://www.backalleycoder.com/2013/03/18/cross-browser-event-based-element-resize-detection/
如何使用这段代码…
AppConfig.addResizeListener(document.getElementById('id'), function () {
//Your code to execute on resize.
});
示例使用的打包代码…
var AppConfig = AppConfig || {};
AppConfig.ResizeListener = (function () {
var attachEvent = document.attachEvent;
var isIE = navigator.userAgent.match(/Trident/);
var requestFrame = (function () {
var raf = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame ||
function (fn) { return window.setTimeout(fn, 20); };
return function (fn) { return raf(fn); };
})();
var cancelFrame = (function () {
var cancel = window.cancelAnimationFrame || window.mozCancelAnimationFrame || window.webkitCancelAnimationFrame ||
window.clearTimeout;
return function (id) { return cancel(id); };
})();
function resizeListener(e) {
var win = e.target || e.srcElement;
if (win.__resizeRAF__) cancelFrame(win.__resizeRAF__);
win.__resizeRAF__ = requestFrame(function () {
var trigger = win.__resizeTrigger__;
trigger.__resizeListeners__.forEach(function (fn) {
fn.call(trigger, e);
});
});
}
function objectLoad(e) {
this.contentDocument.defaultView.__resizeTrigger__ = this.__resizeElement__;
this.contentDocument.defaultView.addEventListener('resize', resizeListener);
}
AppConfig.addResizeListener = function (element, fn) {
if (!element.__resizeListeners__) {
element.__resizeListeners__ = [];
if (attachEvent) {
element.__resizeTrigger__ = element;
element.attachEvent('onresize', resizeListener);
} else {
if (getComputedStyle(element).position === 'static') element.style.position = 'relative';
var obj = element.__resizeTrigger__ = document.createElement('object');
obj.setAttribute('style', 'display: block; position: absolute; top: 0; left: 0; height: 100%; width: 100%; overflow: hidden; pointer-events: none; z-index: -1;');
obj.__resizeElement__ = element;
obj.onload = objectLoad;
obj.type = 'text/html';
if (isIE) element.appendChild(obj);
obj.data = 'about:blank';
if (!isIE) element.appendChild(obj);
}
}
element.__resizeListeners__.push(fn);
};
AppConfig.removeResizeListener = function (element, fn) {
element.__resizeListeners__.splice(element.__resizeListeners__.indexOf(fn), 1);
if (!element.__resizeListeners__.length) {
if (attachEvent) element.detachEvent('onresize', resizeListener);
else {
element.__resizeTrigger__.contentDocument.defaultView.removeEventListener('resize', resizeListener);
element.__resizeTrigger__ = !element.removeChild(element.__resizeTrigger__);
}
}
}
})();
注意:AppConfig是我用于组织可重用函数的名称空间/对象。请随意搜索并替换任何您想要的名称。
有一种非常有效的方法来确定元素的大小是否已经改变。
http://marcj.github.io/css-element-queries/
这个库有一个resizessensor类，可以用于调整大小检测。它使用基于事件的方法，所以它非常快，而且不会浪费CPU时间。
例子:
new ResizeSensor(jQuery('#divId'), function(){
console.log('content dimension changed');
});
请不要使用jQuery onresize插件，因为它使用setTimeout()结合在循环中读取DOM clienttheight /clientWidth属性来检查更改。这是令人难以置信的缓慢和不准确，因为它会导致布局抖动。
披露:我与这个库直接相关。
从长远来看，您将能够使用ResizeObserver。
new ResizeObserver(callback).observe(element);
不幸的是，目前许多浏览器默认不支持它。
同时，您可以像下面这样使用函数。因为，大部分元素大小的变化将来自窗口大小的调整或DOM中的某些更改。你可以通过窗口的resize事件来监听窗口的大小调整，也可以使用MutationObserver监听DOM的变化。
下面是一个函数的例子，当提供的元素的大小因为这两个事件中的任何一个而改变时，它会回调你:
var onResize = function(element, callback) {
if (!onResize.watchedElementData) {
// First time we are called, create a list of watched elements
// and hook up the event listeners.
onResize.watchedElementData = [];
var checkForChanges = function() {
onResize.watchedElementData.forEach(function(data) {
if (data.element.offsetWidth !== data.offsetWidth ||
data.element.offsetHeight !== data.offsetHeight) {
data.offsetWidth = data.element.offsetWidth;
data.offsetHeight = data.element.offsetHeight;
data.callback();
}
});
};
// Listen to the window's size changes
window.addEventListener('resize', checkForChanges);
// Listen to changes on the elements in the page that affect layout
var observer = new MutationObserver(checkForChanges);
observer.observe(document.body, {
attributes: true,
childList: true,
characterData: true,
subtree: true
});
}
// Save the element we are watching
onResize.watchedElementData.push({
element: element,
offsetWidth: element.offsetWidth,
offsetHeight: element.offsetHeight,
callback: callback
});
};
