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>
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);
});
当MarcJ的解决方案不起作用时，我发现这个库可以工作:
https://github.com/sdecima/javascript-detect-element-resize
它是非常轻量级的，甚至可以通过CSS或简单的HTML加载/渲染来检测自然的大小调整。
代码示例(摘自链接):
<script type="text/javascript" src="detect-element-resize.js"></script>
<script type="text/javascript">
var resizeElement = document.getElementById('resizeElement'),
resizeCallback = function() {
/* do something */
};
addResizeListener(resizeElement, resizeCallback);
removeResizeListener(resizeElement, resizeCallback);
</script>
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。
这是一个非常老的问题，但我想我会把我的解决方案贴出来。
我尝试使用resizsensor，因为每个人似乎都对它有很大的好感。在实现之后，我意识到在底层，元素查询要求所讨论的元素具有相对位置或绝对位置，这不适用于我的情况。
我最终用Rxjs间隔来处理这个问题，而不是像以前的实现那样直接使用setTimeout或requestAnimationFrame。
间隔的可观察对象的好处在于，你可以修改流，但任何其他可观察对象都可以被处理。对我来说，一个基本的实现就足够了，但是你可以疯狂地做各种各样的合并等等。
在下面的例子中，我正在跟踪内部(绿色)div的宽度变化。它的宽度设置为50%，但max-width为200px。拖动滑块会影响包装器(灰色)div的宽度。你可以看到，只有当内部div的宽度发生变化时，可观察对象才会触发，只有当外部div的宽度小于400px时才会发生这种情况。
const { interval } = rxjs;
const { distinctUntilChanged, map, filter } = rxjs.operators;
const wrapper = document.getElementById('my-wrapper');
const input = document.getElementById('width-input');
function subscribeToResize() {
const timer = interval(100);
const myDiv = document.getElementById('my-div');
const widthElement = document.getElementById('width');
const isMax = document.getElementById('is-max');
/*
NOTE: This is the important bit here
*/
timer
.pipe(
map(() => myDiv ? Math.round(myDiv.getBoundingClientRect().width) : 0),
distinctUntilChanged(),
// adding a takeUntil(), here as well would allow cleanup when the component is destroyed
)
.subscribe((width) => {
widthElement.innerHTML = width;
isMax.innerHTML = width === 200 ? 'Max width' : '50% width';
});
}
function defineRange() {
input.min = 200;
input.max = window.innerWidth;
input.step = 10;
input.value = input.max - 50;
}
function bindInputToWrapper() {
input.addEventListener('input', (event) => {
wrapper.style.width = `${event.target.value}px`;
});
}
defineRange();
subscribeToResize();
bindInputToWrapper();
.inner {
width: 50%;
max-width: 200px;
}
/* Aesthetic styles only */
.inner {
background: #16a085;
}
.wrapper {
background: #ecf0f1;
color: white;
margin-top: 24px;
}
.content {
padding: 12px;
}
body {
font-family: sans-serif;
font-weight: bold;
}
<script src="https://unpkg.com/rxjs/bundles/rxjs.umd.min.js"></script>
<h1>Resize Browser width</h1>
<label for="width-input">Adjust the width of the wrapper element</label>
<div>
<input type="range" id="width-input">
</div>
<div id="my-wrapper" class="wrapper">
<div id="my-div" class="inner">
<div class="content">
Width: <span id="width"></span>px
<div id="is-max"></div>
</div>
</div>
</div>
