下面的解决方案告诉你如何用javascript的attr属性更新伪元素。

在HTML中添加一个属性，你可以用javascript setAttribute操作它。

<div 
 id="inputBoxParent" 
 count="0">
      ...
</div>

用js更新

inputBoxParent.setAttribute('count', value.length)

CSS -在伪元素中添加内容为attr(attributeName)

.input-box-container::after{
  content: attr(count);
}

你完蛋了!!

const inputBoxParent = document.getElementById("inputBoxParent"); const handleOnChange = (value) => { inputBoxParent.setAttribute('count', value.length) } .input-box-container { position: relative; width: 200px; } .input-box-container::after{ position: absolute; bottom: 8px; right: 10px; height: 10px; width: 20px; content: attr(count); } <h4> Type some text inside the box and click outside to see resule i.e. pseudo element content change</h4> <div id="inputBoxParent" class="input-box-container" count="0"> <input type="text" id="inputBox" placeholder="type some thing" onchange="handleOnChange(this.value)" onkeyup="handleOnChange(this.value)" /> </div>

只需要在之前或之后设置伪样式来继承，然后用javascript设置父样式。

例如，我想改变:before的颜色样式，然后我设置:

.my-style::before{
color: inherit;
}

然后我用javascript改变了.my-style元素的颜色样式:

document.querySelector(".my-style").style.color = red;

工作完成了，超级简单

$ (' .span ')。attr(“data-txt”、“foo”); $ (' .span ')。点击(函数(){ (美元)。Attr ('data-txt'，"任何其他文本"); }) .span { ｝ .span:{后 内容:attr (data-txt); ｝ < script src = " https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js " > < /脚本> < div class =“跨度”> < / div >

根据克里斯蒂安的建议，你还可以这样做:

$('head').append("<style>.span::after{ content:'bar' }</style>");

下面的解决方案告诉你如何用javascript的attr属性更新伪元素。

在HTML中添加一个属性，你可以用javascript setAttribute操作它。

<div 
 id="inputBoxParent" 
 count="0">
      ...
</div>

用js更新

inputBoxParent.setAttribute('count', value.length)

CSS -在伪元素中添加内容为attr(attributeName)

.input-box-container::after{
  content: attr(count);
}

你完蛋了!!

const inputBoxParent = document.getElementById("inputBoxParent"); const handleOnChange = (value) => { inputBoxParent.setAttribute('count', value.length) } .input-box-container { position: relative; width: 200px; } .input-box-container::after{ position: absolute; bottom: 8px; right: 10px; height: 10px; width: 20px; content: attr(count); } <h4> Type some text inside the box and click outside to see resule i.e. pseudo element content change</h4> <div id="inputBoxParent" class="input-box-container" count="0"> <input type="text" id="inputBox" placeholder="type some thing" onchange="handleOnChange(this.value)" onkeyup="handleOnChange(this.value)" /> </div>

你可以使用我的插件来实现这个目的。

JQuery:

(function() { $.pseudoElements = { length: 0 }; var setPseudoElement = function(parameters) { if (typeof parameters.argument === 'object' || (parameters.argument !== undefined && parameters.property !== undefined)) { for (var element of parameters.elements.get()) { if (!element.pseudoElements) element.pseudoElements = { styleSheet: null, before: { index: null, properties: null }, after: { index: null, properties: null }, id: null }; var selector = (function() { if (element.pseudoElements.id !== null) { if (Number(element.getAttribute('data-pe--id')) !== element.pseudoElements.id) element.setAttribute('data-pe--id', element.pseudoElements.id); return '[data-pe--id="' + element.pseudoElements.id + '"]::' + parameters.pseudoElement; } else { var id = $.pseudoElements.length; $.pseudoElements.length++ element.pseudoElements.id = id; element.setAttribute('data-pe--id', id); return '[data-pe--id="' + id + '"]::' + parameters.pseudoElement; }; })(); if (!element.pseudoElements.styleSheet) { if (document.styleSheets[0]) { element.pseudoElements.styleSheet = document.styleSheets[0]; } else { var styleSheet = document.createElement('style'); document.head.appendChild(styleSheet); element.pseudoElements.styleSheet = styleSheet.sheet; }; }; if (element.pseudoElements[parameters.pseudoElement].properties && element.pseudoElements[parameters.pseudoElement].index) { element.pseudoElements.styleSheet.deleteRule(element.pseudoElements[parameters.pseudoElement].index); }; if (typeof parameters.argument === 'object') { parameters.argument = $.extend({}, parameters.argument); if (!element.pseudoElements[parameters.pseudoElement].properties && !element.pseudoElements[parameters.pseudoElement].index) { var newIndex = element.pseudoElements.styleSheet.rules.length || element.pseudoElements.styleSheet.cssRules.length || element.pseudoElements.styleSheet.length; element.pseudoElements[parameters.pseudoElement].index = newIndex; element.pseudoElements[parameters.pseudoElement].properties = parameters.argument; }; var properties = ''; for (var property in parameters.argument) { if (typeof parameters.argument[property] === 'function') element.pseudoElements[parameters.pseudoElement].properties[property] = parameters.argument[property](); else element.pseudoElements[parameters.pseudoElement].properties[property] = parameters.argument[property]; }; for (var property in element.pseudoElements[parameters.pseudoElement].properties) { properties += property + ': ' + element.pseudoElements[parameters.pseudoElement].properties[property] + ' !important; '; }; element.pseudoElements.styleSheet.addRule(selector, properties, element.pseudoElements[parameters.pseudoElement].index); } else if (parameters.argument !== undefined && parameters.property !== undefined) { if (!element.pseudoElements[parameters.pseudoElement].properties && !element.pseudoElements[parameters.pseudoElement].index) { var newIndex = element.pseudoElements.styleSheet.rules.length || element.pseudoElements.styleSheet.cssRules.length || element.pseudoElements.styleSheet.length; element.pseudoElements[parameters.pseudoElement].index = newIndex; element.pseudoElements[parameters.pseudoElement].properties = {}; }; if (typeof parameters.property === 'function') element.pseudoElements[parameters.pseudoElement].properties[parameters.argument] = parameters.property(); else element.pseudoElements[parameters.pseudoElement].properties[parameters.argument] = parameters.property; var properties = ''; for (var property in element.pseudoElements[parameters.pseudoElement].properties) { properties += property + ': ' + element.pseudoElements[parameters.pseudoElement].properties[property] + ' !important; '; }; element.pseudoElements.styleSheet.addRule(selector, properties, element.pseudoElements[parameters.pseudoElement].index); }; }; return $(parameters.elements); } else if (parameters.argument !== undefined && parameters.property === undefined) { var element = $(parameters.elements).get(0); var windowStyle = window.getComputedStyle( element, '::' + parameters.pseudoElement ).getPropertyValue(parameters.argument); if (element.pseudoElements) { return $(parameters.elements).get(0).pseudoElements[parameters.pseudoElement].properties[parameters.argument] || windowStyle; } else { return windowStyle || null; }; } else { console.error('Invalid values!'); return false; }; }; $.fn.cssBefore = function(argument, property) { return setPseudoElement({ elements: this, pseudoElement: 'before', argument: argument, property: property }); }; $.fn.cssAfter = function(argument, property) { return setPseudoElement({ elements: this, pseudoElement: 'after', argument: argument, property: property }); }; })(); $(function() { $('.element').cssBefore('content', '"New before!"'); }); .element { width: 480px; margin: 0 auto; border: 2px solid red; } .element::before { content: 'Old before!'; } <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script> <div class="element"></div>

应该指定值，就像在jQuery.css的普通函数中一样

此外，你还可以获得pseudo-element参数的值，就像在jQuery.css的普通函数中一样:

console.log( $(element).cssBefore(parameter) );

JS:

(function() { document.pseudoElements = { length: 0 }; var setPseudoElement = function(parameters) { if (typeof parameters.argument === 'object' || (parameters.argument !== undefined && parameters.property !== undefined)) { if (!parameters.element.pseudoElements) parameters.element.pseudoElements = { styleSheet: null, before: { index: null, properties: null }, after: { index: null, properties: null }, id: null }; var selector = (function() { if (parameters.element.pseudoElements.id !== null) { if (Number(parameters.element.getAttribute('data-pe--id')) !== parameters.element.pseudoElements.id) parameters.element.setAttribute('data-pe--id', parameters.element.pseudoElements.id); return '[data-pe--id="' + parameters.element.pseudoElements.id + '"]::' + parameters.pseudoElement; } else { var id = document.pseudoElements.length; document.pseudoElements.length++ parameters.element.pseudoElements.id = id; parameters.element.setAttribute('data-pe--id', id); return '[data-pe--id="' + id + '"]::' + parameters.pseudoElement; }; })(); if (!parameters.element.pseudoElements.styleSheet) { if (document.styleSheets[0]) { parameters.element.pseudoElements.styleSheet = document.styleSheets[0]; } else { var styleSheet = document.createElement('style'); document.head.appendChild(styleSheet); parameters.element.pseudoElements.styleSheet = styleSheet.sheet; }; }; if (parameters.element.pseudoElements[parameters.pseudoElement].properties && parameters.element.pseudoElements[parameters.pseudoElement].index) { parameters.element.pseudoElements.styleSheet.deleteRule(parameters.element.pseudoElements[parameters.pseudoElement].index); }; if (typeof parameters.argument === 'object') { parameters.argument = (function() { var cloneObject = typeof parameters.argument.pop === 'function' ? [] : {}; for (var property in parameters.argument) { cloneObject[property] = parameters.argument[property]; }; return cloneObject; })(); if (!parameters.element.pseudoElements[parameters.pseudoElement].properties && !parameters.element.pseudoElements[parameters.pseudoElement].index) { var newIndex = parameters.element.pseudoElements.styleSheet.rules.length || parameters.element.pseudoElements.styleSheet.cssRules.length || parameters.element.pseudoElements.styleSheet.length; parameters.element.pseudoElements[parameters.pseudoElement].index = newIndex; parameters.element.pseudoElements[parameters.pseudoElement].properties = parameters.argument; }; var properties = ''; for (var property in parameters.argument) { if (typeof parameters.argument[property] === 'function') parameters.element.pseudoElements[parameters.pseudoElement].properties[property] = parameters.argument[property](); else parameters.element.pseudoElements[parameters.pseudoElement].properties[property] = parameters.argument[property]; }; for (var property in parameters.element.pseudoElements[parameters.pseudoElement].properties) { properties += property + ': ' + parameters.element.pseudoElements[parameters.pseudoElement].properties[property] + ' !important; '; }; parameters.element.pseudoElements.styleSheet.addRule(selector, properties, parameters.element.pseudoElements[parameters.pseudoElement].index); } else if (parameters.argument !== undefined && parameters.property !== undefined) { if (!parameters.element.pseudoElements[parameters.pseudoElement].properties && !parameters.element.pseudoElements[parameters.pseudoElement].index) { var newIndex = parameters.element.pseudoElements.styleSheet.rules.length || parameters.element.pseudoElements.styleSheet.cssRules.length || parameters.element.pseudoElements.styleSheet.length; parameters.element.pseudoElements[parameters.pseudoElement].index = newIndex; parameters.element.pseudoElements[parameters.pseudoElement].properties = {}; }; if (typeof parameters.property === 'function') parameters.element.pseudoElements[parameters.pseudoElement].properties[parameters.argument] = parameters.property(); else parameters.element.pseudoElements[parameters.pseudoElement].properties[parameters.argument] = parameters.property; var properties = ''; for (var property in parameters.element.pseudoElements[parameters.pseudoElement].properties) { properties += property + ': ' + parameters.element.pseudoElements[parameters.pseudoElement].properties[property] + ' !important; '; }; parameters.element.pseudoElements.styleSheet.addRule(selector, properties, parameters.element.pseudoElements[parameters.pseudoElement].index); }; } else if (parameters.argument !== undefined && parameters.property === undefined) { var windowStyle = window.getComputedStyle( parameters.element, '::' + parameters.pseudoElement ).getPropertyValue(parameters.argument); if (parameters.element.pseudoElements) { return parameters.element.pseudoElements[parameters.pseudoElement].properties[parameters.argument] || windowStyle; } else { return windowStyle || null; }; } else { console.error('Invalid values!'); return false; }; }; Object.defineProperty(Element.prototype, 'styleBefore', { enumerable: false, value: function(argument, property) { return setPseudoElement({ element: this, pseudoElement: 'before', argument: argument, property: property }); } }); Object.defineProperty(Element.prototype, 'styleAfter', { enumerable: false, value: function(argument, property) { return setPseudoElement({ element: this, pseudoElement: 'after', argument: argument, property: property }); } }); })(); document.querySelector('.element').styleBefore('content', '"New before!"'); .element { width: 480px; margin: 0 auto; border: 2px solid red; } .element::before { content: 'Old before!'; } <div class="element"></div>

GitHub: https://github.com/yuri-spivak/managing-the-properties-of-pseudo-elements/