div元素的Onresize？

Question

Visual Studio突出显示了我的div标记的onresize属性，并指出它不是HTML5的有效属性。这是真的吗？我应该用什么来代替呢？这看起来有点愚蠢，事情就是这样。

Answer 1

微软的on浏览器在所有的超文本标记语言元素上都支持onresize。在所有其他浏览器中，onresize仅在window对象中可用。https://developer.mozilla.org/en-US/docs/Web/API/Window.onresize

如果你想让div在所有浏览器中都有onresize，请检查以下内容：

http://marcj.github.io/css-element-queries/

这个库有一个可用于resize检测的类ResizeSensor。

Answer 2

将以下CSS和JavaScript添加到您的页面中，并使用addResizeListener和removeResizeListener方法侦听元素大小的更改(有关更多详细信息，请在博客中发布：http://www.backalleycoder.com/2013/03/18/cross-browser-event-based-element-resize-detection/)：

调整传感器CSS

.resize-triggers {
    visibility: hidden;
}

.resize-triggers, .resize-triggers > div, .contract-trigger:before {
  content: " ";
  display: block;
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  overflow: hidden;
}

.resize-triggers > div {
  background: #eee;
  overflow: auto;
}

.contract-trigger:before {
  width: 200%;
  height: 200%;
}

调整大小事件方法

以下是启用resize事件侦听所需的JavaScript。前两个函数是在主addResizeListener和removeResizeListener方法中使用的先决条件。

(function(){

var attachEvent = document.attachEvent;

if (!attachEvent) {
    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 resetTriggers(element){
        var triggers = element.__resizeTriggers__,
            expand = triggers.firstElementChild,
            contract = triggers.lastElementChild,
            expandChild = expand.firstElementChild;
        contract.scrollLeft = contract.scrollWidth;
        contract.scrollTop = contract.scrollHeight;
        expandChild.style.width = expand.offsetWidth + 1 + 'px';
        expandChild.style.height = expand.offsetHeight + 1 + 'px';
        expand.scrollLeft = expand.scrollWidth;
        expand.scrollTop = expand.scrollHeight;
    };

    function checkTriggers(element){
      return element.offsetWidth != element.__resizeLast__.width ||
             element.offsetHeight != element.__resizeLast__.height;
    }

    function scrollListener(e){
        var element = this;
        resetTriggers(this);
        if (this.__resizeRAF__) cancelFrame(this.__resizeRAF__);
        this.__resizeRAF__ = requestFrame(function(){
            if (checkTriggers(element)) {
                element.__resizeLast__.width = element.offsetWidth;
                element.__resizeLast__.height = element.offsetHeight;
                element.__resizeListeners__.forEach(function(fn){
                    fn.call(element, e);
                });
            }
        });
    };
}

window.addResizeListener = function(element, fn){
    if (attachEvent) element.attachEvent('resize', fn);
    else {
        if (!element.__resizeTriggers__) {
            if (getComputedStyle(element).position == 'static') element.style.position = 'relative';
            element.__resizeLast__ = {};
            element.__resizeListeners__ = [];
            (element.__resizeTriggers__ = document.createElement('div')).className = 'resize-triggers';
            element.__resizeTriggers__.innerHTML = '<div class="expand-trigger"><div></div></div>' +
                                                   '<div class="contract-trigger"></div>';
            element.appendChild(element.__resizeTriggers__);
            resetTriggers(element);
            element.addEventListener('scroll', scrollListener, true);
        }
        element.__resizeListeners__.push(fn);
    }
};

window.removeResizeListener = function(element, fn){
    if (attachEvent) element.detachEvent('resize', fn);
    else {
        element.__resizeListeners__.splice(element.__resizeListeners__.indexOf(fn), 1);
        if (!element.__resizeListeners__.length) {
            element.removeEventListener('scroll', scrollListener);
            element.__resizeTriggers__ = !element.removeChild(element.__resizeTriggers__);
        }
    }
}

})();

Demo-licious!

下面是该方法的伪代码用法。

var myElement = document.getElementById('my_element'),
    myResizeFn = function(){
        /* do something on resize */
    };
addResizeListener(myElement, myResizeFn);
removeResizeListener(myElement, myResizeFn);

Answer 3

规范中只有Window.onResize。请记住，每个IFrame元素都会创建支持onResize的新Window对象。因此，IMO检测元素大小更改的最可靠方法是将隐藏的iframe附加到元素。

如果您对整洁和便携的解决方案感兴趣，请查看this plugin。只需要一行代码就可以监听更改div的宽度或高度的事件。

<!-- (1) include plugin script in a page -->
<script src="/src/jquery-element-onresize.js"></script>

// (2) use the detectResizing plugin to monitor changes to the element's size:
$monitoredElement.detectResizing({ onResize: monitoredElement_onResize });

// (3) write a function to react on changes:
function monitoredElement_onResize() {    
    // logic here...
}