原文：https://developer.mozilla.org/zh-CN/docs/Web/Guide/HTML/Content_Editable
概述
在HTML中，任何元素都可以编辑。通过使用一些JavaScript事件处理程序，您可以将您的网页转换成一个完整而快速的富文本编辑器。本文提供了有关此功能的一些信息。
在HTML5中,任何元素都是可编辑的. 这项特性在很久以前就已经被提出,不过直到现在才被WHATWG (当前HTML标准)组织标准化. 通过一些javascript事件处理函数,你可以把自己的网页转换成完整快速的富文本编辑器.
它是如何工作的?
只要将HTML元素的contenteditable属性值设置 true, 就可以激活编辑模式，那么该元素范围中的内容都是可编辑的.
例子
- 这是一个简单的例子，创建一个<div>元素，用户可以编辑其内容。
<div contenteditable="true">
This text can be edited by the user.
</div>
- 另一个使用LocalStorage技术配合的content editable例子演示
可执行命令
当一个HTML标签的contenteditable属性设置为true时，document.execCommand() 方法就生效了。这可以让你运行命令去操作可编辑区域的内容。大多数命令会影响选择的文档，例如，应用一个文本样式（粗体，斜体等等），或者当插入新标签时（例如添加一个链接），或者影响了一整行（例如文本缩进）。当使用contentEditable时，调用execCommand()方法将影响到当前的激活的可编辑元素。
标签生成的差异
一直以来，在不同的浏览器使用contenteditable效果不是很好，因为不同浏览器生成标签的规则不一样。例如，即使是像“输入即输出”来在一个可编辑标签内创建一个新行，在主流浏览器中都会有很多大不同。（Firefox插入
标签，IE/Opera插入<p>，Chrome和Safari插入<div>）
幸运的是，在现代浏览器中，插入标签是一致的。例如在Firefox 55中，将之前的
标签，改为<div>标签，与Chrome以及现代的Opera, Edge, and Safari一致。
在上面的例子中可以试一下。
提醒：老版本的IE，一直是在用<p>，没有更新成div。
如果你想使用段落分离器，上面提及的浏览器均支持document.execCommand，提供了一个"DefaultPragraphSeparator"接口，允许我们来改变默认插入的标签，例如，想用<p>来分段：
document.execCommand("DefaultParagraphSeparator", false, "p");
安全性
由于安全原因，Firefox不允许使用剪贴板的copy ，paste等等默认功能。你可以通过使用在firefox浏览器地址栏中输入about:config，从而去启用他们。
user_pref("capability.policy.policynames", "allowclipboard");
user_pref("capability.policy.allowclipboard.sites", "https://www.mozilla.org");
user_pref("capability.policy.allowclipboard.Clipboard.cutcopy", "allAccess");
user_pref("capability.policy.allowclipboard.Clipboard.paste", "allAccess");
例子：一个简单但是完整的富文本编辑器
<!doctype html>
<html>
<head>
<title>Rich Text Editor</title>
<script type="text/javascript">
var oDoc, sDefTxt;
function initDoc() {
oDoc = document.getElementById("textBox");
sDefTxt = oDoc.innerHTML;
if (document.compForm.switchMode.checked) { setDocMode(true); }
}
function formatDoc(sCmd, sValue) {
if (validateMode()) { document.execCommand(sCmd, false, sValue); oDoc.focus(); }
}
function validateMode() {
if (!document.compForm.switchMode.checked) { return true ; }
alert("Uncheck \"Show HTML\".");
oDoc.focus();
return false;
}
function setDocMode(bToSource) {
var oContent;
if (bToSource) {
oContent = document.createTextNode(oDoc.innerHTML);
oDoc.innerHTML = "";
var oPre = document.createElement("pre");
oDoc.contentEditable = false;
oPre.id = "sourceText";
oPre.contentEditable = true;
oPre.appendChild(oContent);
oDoc.appendChild(oPre);
document.execCommand("defaultParagraphSeparator", false, "div");
} else {
if (document.all) {
oDoc.innerHTML = oDoc.innerText;
} else {
oContent = document.createRange();
oContent.selectNodeContents(oDoc.firstChild);
oDoc.innerHTML = oContent.toString();
}
oDoc.contentEditable = true;
}
oDoc.focus();
}
function printDoc() {
if (!validateMode()) { return; }
var oPrntWin = window.open("","_blank","width=450,height=470,left=400,top=100,menubar=yes,toolbar=no,location=no,scrollbars=yes");
oPrntWin.document.open();
oPrntWin.document.write("<!doctype html><html><head><title>Print<\/title><\/head><body onload=\"print();\">" + oDoc.innerHTML + "<\/body><\/html>");
oPrntWin.document.close();
}
</script>
<style type="text/css">
.intLink { cursor: pointer; }
img.intLink { border: 0; }
#toolBar1 select { font-size:10px; }
#textBox {
width: 540px;
height: 200px;
border: 1px #000000 solid;
padding: 12px;
overflow: scroll;
}
#textBox #sourceText {
padding: 0;
margin: 0;
min-width: 498px;
min-height: 200px;
}
#editMode label { cursor: pointer; }
</style>
</head>
<body onload="initDoc();">
<form name="compForm" method="post" action="sample.php" onsubmit="if(validateMode()){this.myDoc.value=oDoc.innerHTML;return true;}return false;">
<input type="hidden" name="myDoc">
<div id="toolBar1">
<select onchange="formatDoc('formatblock',this[this.selectedIndex].value);this.selectedIndex=0;">
<option selected>- formatting -</option>
<option value="h1">Title 1 <h1></option>
<option value="h2">Title 2 <h2></option>
<option value="h3">Title 3 <h3></option>
<option value="h4">Title 4 <h4></option>
<option value="h5">Title 5 <h5></option>
<option value="h6">Subtitle <h6></option>
<option value="p">Paragraph <p></option>
<option value="pre">Preformatted <pre></option>
</select>
<select onchange="formatDoc('fontname',this[this.selectedIndex].value);this.selectedIndex=0;">
<option class="heading" selected>- font -</option>
<option>Arial</option>
<option>Arial Black</option>
<option>Courier New</option>
<option>Times New Roman</option>
</select>
<select onchange="formatDoc('fontsize',this[this.selectedIndex].value);this.selectedIndex=0;">
<option class="heading" selected>- size -</option>
<option value="1">Very small</option>
<option value="2">A bit small</option>
<option value="3">Normal</option>
<option value="4">Medium-large</option>
<option value="5">Big</option>
<option value="6">Very big</option>
<option value="7">Maximum</option>
</select>
<select onchange="formatDoc('forecolor',this[this.selectedIndex].value);this.selectedIndex=0;">
<option class="heading" selected>- color -</option>
<option value="red">Red</option>
<option value="blue">Blue</option>
<option value="green">Green</option>
<option value="black">Black</option>
</select>
<select onchange="formatDoc('backcolor',this[this.selectedIndex].value);this.selectedIndex=0;">
<option class="heading" selected>- background -</option>
<option value="red">Red</option>
<option value="green">Green</option>
<option value="black">Black</option>
</select>
</div>
<div id="toolBar2">
<img class="intLink" title="Clean" onclick="if(validateMode()&&confirm('Are you sure?')){oDoc.innerHTML=sDefTxt};" src="data:image/gif;base64,R0lGODlhFgAWAIQbAD04KTRLYzFRjlldZl9vj1dusY14WYODhpWIbbSVFY6O7IOXw5qbms+wUbCztca0ccS4kdDQjdTLtMrL1O3YitHa7OPcsd/f4PfvrvDv8Pv5xv///////////////////yH5BAEKAB8ALAAAAAAWABYAAAV84CeOZGmeaKqubMteyzK547QoBcFWTm/jgsHq4rhMLoxFIehQQSAWR+Z4IAyaJ0kEgtFoLIzLwRE4oCQWrxoTOTAIhMCZ0tVgMBQKZHAYyFEWEV14eQ8IflhnEHmFDQkAiSkQCI2PDC4QBg+OAJc0ewadNCOgo6anqKkoIQA7" />
<img class="intLink" title="Print" onclick="printDoc();" src="data:image/png;base64,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">
<img class="intLink" title="Undo" onclick="formatDoc('undo');" src="data:image/gif;base64,R0lGODlhFgAWAOMKADljwliE33mOrpGjuYKl8aezxqPD+7/I19DV3NHa7P///////////////////////yH5BAEKAA8ALAAAAAAWABYAAARR8MlJq7046807TkaYeJJBnES4EeUJvIGapWYAC0CsocQ7SDlWJkAkCA6ToMYWIARGQF3mRQVIEjkkSVLIbSfEwhdRIH4fh/DZMICe3/C4nBQBADs=" />
<img class="intLink" title="Redo" onclick="formatDoc('redo');" src="data:image/gif;base64,R0lGODlhFgAWAMIHAB1ChDljwl9vj1iE34Kl8aPD+7/I1////yH5BAEKAAcALAAAAAAWABYAAANKeLrc/jDKSesyphi7SiEgsVXZEATDICqBVJjpqWZt9NaEDNbQK1wCQsxlYnxMAImhyDoFAElJasRRvAZVRqqQXUy7Cgx4TC6bswkAOw==" />
<img class="intLink" title="Remove formatting" onclick="formatDoc('removeFormat')" src="data:image/png;base64,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">
<img class="intLink" title="Bold" onclick="formatDoc('bold');" src="data:image/gif;base64,R0lGODlhFgAWAID/AMDAwAAAACH5BAEAAAAALAAAAAAWABYAQAInhI+pa+H9mJy0LhdgtrxzDG5WGFVk6aXqyk6Y9kXvKKNuLbb6zgMFADs=" />
<img class="intLink" title="Italic" onclick="formatDoc('italic');" src="data:image/gif;base64,R0lGODlhFgAWAKEDAAAAAF9vj5WIbf///yH5BAEAAAMALAAAAAAWABYAAAIjnI+py+0Po5x0gXvruEKHrF2BB1YiCWgbMFIYpsbyTNd2UwAAOw==" />
<img class="intLink" title="Underline" onclick="formatDoc('underline');" src="data:image/gif;base64,R0lGODlhFgAWAKECAAAAAF9vj////////yH5BAEAAAIALAAAAAAWABYAAAIrlI+py+0Po5zUgAsEzvEeL4Ea15EiJJ5PSqJmuwKBEKgxVuXWtun+DwxCCgA7" />
<img class="intLink" title="Left align" onclick="formatDoc('justifyleft');" src="data:image/gif;base64,R0lGODlhFgAWAID/AMDAwAAAACH5BAEAAAAALAAAAAAWABYAQAIghI+py+0Po5y02ouz3jL4D4JMGELkGYxo+qzl4nKyXAAAOw==" />
<img class="intLink" title="Center align" onclick="formatDoc('justifycenter');" src="data:image/gif;base64,R0lGODlhFgAWAID/AMDAwAAAACH5BAEAAAAALAAAAAAWABYAQAIfhI+py+0Po5y02ouz3jL4D4JOGI7kaZ5Bqn4sycVbAQA7" />
<img class="intLink" title="Right align" onclick="formatDoc('justifyright');" src="data:image/gif;base64,R0lGODlhFgAWAID/AMDAwAAAACH5BAEAAAAALAAAAAAWABYAQAIghI+py+0Po5y02ouz3jL4D4JQGDLkGYxouqzl43JyVgAAOw==" />
<img class="intLink" title="Numbered list" onclick="formatDoc('insertorderedlist');" src="data:image/gif;base64,R0lGODlhFgAWAMIGAAAAADljwliE35GjuaezxtHa7P///////yH5BAEAAAcALAAAAAAWABYAAAM2eLrc/jDKSespwjoRFvggCBUBoTFBeq6QIAysQnRHaEOzyaZ07Lu9lUBnC0UGQU1K52s6n5oEADs=" />
<img class="intLink" title="Dotted list" onclick="formatDoc('insertunorderedlist');" src="data:image/gif;base64,R0lGODlhFgAWAMIGAAAAAB1ChF9vj1iE33mOrqezxv///////yH5BAEAAAcALAAAAAAWABYAAAMyeLrc/jDKSesppNhGRlBAKIZRERBbqm6YtnbfMY7lud64UwiuKnigGQliQuWOyKQykgAAOw==" />
<img class="intLink" title="Quote" onclick="formatDoc('formatblock','blockquote');" src="data:image/gif;base64,R0lGODlhFgAWAIQXAC1NqjFRjkBgmT9nqUJnsk9xrFJ7u2R9qmKBt1iGzHmOrm6Sz4OXw3Odz4Cl2ZSnw6KxyqO306K63bG70bTB0rDI3bvI4P///////////////////////////////////yH5BAEKAB8ALAAAAAAWABYAAAVP4CeOZGmeaKqubEs2CekkErvEI1zZuOgYFlakECEZFi0GgTGKEBATFmJAVXweVOoKEQgABB9IQDCmrLpjETrQQlhHjINrTq/b7/i8fp8PAQA7" />
<img class="intLink" title="Delete indentation" onclick="formatDoc('outdent');" src="data:image/gif;base64,R0lGODlhFgAWAMIHAAAAADljwliE35GjuaezxtDV3NHa7P///yH5BAEAAAcALAAAAAAWABYAAAM2eLrc/jDKCQG9F2i7u8agQgyK1z2EIBil+TWqEMxhMczsYVJ3e4ahk+sFnAgtxSQDqWw6n5cEADs=" />
<img class="intLink" title="Add indentation" onclick="formatDoc('indent');" src="data:image/gif;base64,R0lGODlhFgAWAOMIAAAAADljwl9vj1iE35GjuaezxtDV3NHa7P///////////////////////////////yH5BAEAAAgALAAAAAAWABYAAAQ7EMlJq704650B/x8gemMpgugwHJNZXodKsO5oqUOgo5KhBwWESyMQsCRDHu9VOyk5TM9zSpFSr9gsJwIAOw==" />
<img class="intLink" title="Hyperlink" onclick="var sLnk=prompt('Write the URL here','http:\/\/');if(sLnk&&sLnk!=''&&sLnk!='http://'){formatDoc('createlink',sLnk)}" src="data:image/gif;base64,R0lGODlhFgAWAOMKAB1ChDRLY19vj3mOrpGjuaezxrCztb/I19Ha7Pv8/f///////////////////////yH5BAEKAA8ALAAAAAAWABYAAARY8MlJq7046827/2BYIQVhHg9pEgVGIklyDEUBy/RlE4FQF4dCj2AQXAiJQDCWQCAEBwIioEMQBgSAFhDAGghGi9XgHAhMNoSZgJkJei33UESv2+/4vD4TAQA7" />
<img class="intLink" title="Cut" onclick="formatDoc('cut');" src="data:image/gif;base64,R0lGODlhFgAWAIQSAB1ChBFNsRJTySJYwjljwkxwl19vj1dusYODhl6MnHmOrpqbmpGjuaezxrCztcDCxL/I18rL1P///////////////////////////////////////////////////////yH5BAEAAB8ALAAAAAAWABYAAAVu4CeOZGmeaKqubDs6TNnEbGNApNG0kbGMi5trwcA9GArXh+FAfBAw5UexUDAQESkRsfhJPwaH4YsEGAAJGisRGAQY7UCC9ZAXBB+74LGCRxIEHwAHdWooDgGJcwpxDisQBQRjIgkDCVlfmZqbmiEAOw==" />
<img class="intLink" title="Copy" onclick="formatDoc('copy');" src="data:image/gif;base64,R0lGODlhFgAWAIQcAB1ChBFNsTRLYyJYwjljwl9vj1iE31iGzF6MnHWX9HOdz5GjuYCl2YKl8ZOt4qezxqK63aK/9KPD+7DI3b/I17LM/MrL1MLY9NHa7OPs++bx/Pv8/f///////////////yH5BAEAAB8ALAAAAAAWABYAAAWG4CeOZGmeaKqubOum1SQ/kPVOW749BeVSus2CgrCxHptLBbOQxCSNCCaF1GUqwQbBd0JGJAyGJJiobE+LnCaDcXAaEoxhQACgNw0FQx9kP+wmaRgYFBQNeAoGihCAJQsCkJAKOhgXEw8BLQYciooHf5o7EA+kC40qBKkAAAGrpy+wsbKzIiEAOw==" />
<img class="intLink" title="Paste" onclick="formatDoc('paste');" src="data:image/gif;base64,R0lGODlhFgAWAIQUAD04KTRLY2tXQF9vj414WZWIbXmOrpqbmpGjudClFaezxsa0cb/I1+3YitHa7PrkIPHvbuPs+/fvrvv8/f///////////////////////////////////////////////yH5BAEAAB8ALAAAAAAWABYAAAWN4CeOZGmeaKqubGsusPvBSyFJjVDs6nJLB0khR4AkBCmfsCGBQAoCwjF5gwquVykSFbwZE+AwIBV0GhFog2EwIDchjwRiQo9E2Fx4XD5R+B0DDAEnBXBhBhN2DgwDAQFjJYVhCQYRfgoIDGiQJAWTCQMRiwwMfgicnVcAAAMOaK+bLAOrtLUyt7i5uiUhADs=" />
</div>
<div id="textBox" contenteditable="true"><p>Lorem ipsum</p></div>
<p id="editMode"><input type="checkbox" name="switchMode" id="switchBox" onchange="setDocMode(this.checked);" /> <label for="switchBox">Show HTML</label></p>
<p><input type="submit" value="Send" /></p>
</form>
</body>
</html>
Note: if you want to see how to standardize the creation and the insertion
笔记：如果你想了解更多有关富文本编辑器的内容，可以查看 more complete rich-text editor example.
也可以看看
- HTMLElement.contentEditable
- contenteditable全局属性
- Midas(脚本化的文本编辑组件)
- caret-color 设置文本插入符号的颜色
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