contentEditable,window.getSelection详解---可编辑div，容器，设置/获取光标位置，光标处插入内容及光标的操作

这周碰到一个东西，contentEditable ，它是用来指定一个元素是否是可编辑的，这也是富文本编辑器实现的底层支持，网上关于这部分东西的资料比较少或者不全，所以我来整理下关于这个属性，和可编辑区域的一些操作吧，比如获取光标位置，设置光标，往可编辑区域光标处插入内容等等

HTML中的contentEditable的属性可以打开某些元素的可编辑状态．也许你没用过contentEditable属性．甚至从未听说过．contentEditable的作用相当神奇．可以让div或整个网页，以及span等等元素设置为可写。我们最常用的输入文本内容便是input与textarea，使用contentEditable属性后，可以在div,table,p,span,body,等等很多元素中输入内容．

设置一个容器为可编辑区域:设置contentEditable属性

<body><p contentEditable style="border: 1px solid red;">grsd</p><div  contentEditable style="border: 1px solid red;">rsdgsdg </div>
</body>

设置placeholder：
这个不像表单一样，给属性加上placeholder属性指定值就可以了，还需要配合特殊的样式:empty做设置

 <style type="text/css">.content:empty::before {content: attr(placeholder);font-size: 14px;color: #CCC;line-height: 21px;padding-top: 20px;}.content {border: 1px solid black;}</style><body><div contentEditable class="content" placeholder="请输入不少于150字"></div></body>

回车时，在标记生成上的不同点

因为各个浏览器在标记生成上的不同，因此跨浏览器使用 contenteditable 一直以来都是痛点，例如一些看起来十分简单的事情，如：当你按下Enter/Return键在可编辑区域中创建一个新的文本行时，不同主流浏览器对此有不同处理(Firefox 插入<br>、IE/Opera将使用<p>、 Chrome/Safari 将使用 <div>）幸运的是在现代浏览器中，这些不同都趋于一致了。截止到Firefox 60，火狐开始使用<div>元素来包裹新生成的文本行，以与Chrome, modern Opera, Edge, and Safari.的行为趋于一致

改变回车时插入的标签：
如果你想使用不同的方式创建新的段落,上面所有浏览器都支持document.execCommand方法，该方法提供的 defaultParagraphSeparator 命令能够让你以不同的方式创建新的段落例如, 使用 <p> 元素:

document.execCommand("defaultParagraphSeparator", false, "p");

现在在编辑器中按回车就变成p标签了

document.execCommand的强大：

上面只是document.execCommand的一个命令演示

当一个HTML文档切换到设计模式时，document暴露 execCommand 方法，该方法允许运行命令来操纵可编辑内容区域的元素。
大多数命令影响document的 selection（粗体，斜体等），当其他命令插入新元素（添加链接）或影响整行（缩进）。当使用contentEditable时，调用 execCommand() 将影响当前活动的可编辑元素。

命令很多，这里就不列举出来，具体可以参考官方文档document.execCommand命令大全

基于document.execCommand的这些命令，我们可以做一个小型的富文本编辑器：

<!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 οnlοad=\"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 &lt;h1&gt;</option><option value="h2">Title 2 &lt;h2&gt;</option><option value="h3">Title 3 &lt;h3&gt;</option><option value="h4">Title 4 &lt;h4&gt;</option><option value="h5">Title 5 &lt;h5&gt;</option><option value="h6">Subtitle &lt;h6&gt;</option><option value="p">Paragraph &lt;p&gt;</option><option value="pre">Preformatted &lt;pre&gt;</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();" 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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/I1yH5BAEKAAcALAAAAAAWABYAAANKeLrc/jDKSesyphi7SiEgsVXZEATDICqBVJjpqWZt9NaEDNbQK1wCQsxlYnxMAImhyDoFAElJasRRvAZVRqqQXUy7Cgx4TC6bswkAOw==" /><img class="intLink" title="Remove formatting" onclick="formatDoc('removeFormat')" src="data:image/png;base64,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"><img 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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)}" 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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>

是不是很酷？

window.getSelection()：文档地址

Selection 对象表示用户选择的文本范围或插入符号的当前位置。它代表页面中的文本选区，可能横跨多个元素。文本选区由用户拖拽鼠标经过文字而产生。要获取用于检查或修改的 Selection 对象，请调用 window.getSelection()。

Selection 对象所对应的是用户所选择的 ranges （区域），俗称拖蓝。默认情况下，该函数只针对一个区域，我们可以这样使用这个函数：

var selObj = window.getSelection();
var range  = selObj.getRangeAt(0);

例子： 我写了如下代码来一起探究下这两个是什么东西吧
每次我拖动完，或者点击完鼠标的时候，都会打印selObj，查看selObj对象，看看里面有什么属性

<body><div>我是p标签的内容</div><p>我是p标签的内容</p><ul><li>li1</li><li>li2</li></ul>
</body>
<script type="text/javascript">document.onmouseup=function(){var selObj = window.getSelection();console.log(selObj)var range  = selObj.getRangeAt(0);console.log(range)}
</script>

可以看到window.getSelection()打印的对象就是我们选中区域的对象，对象里面的属性值，我来介绍以下吧

而range对象里面的信息就简洁很多，这个我就不介绍了，和selection对象是一样的

当然range对象和selection对象原型上也有很多的方法提供给我们使用，可以自行查阅文档
selection对象的方法
range对象的方法

我们要说的是基于这些方法，我们如何做到在可编辑的div或容器中往光标处插入内容，返回光标位置

通过js的方式在可编辑区域的光标处插入文本：

方法一：较完整的，考虑兼容，插入后，光标自动设置到插入后的位置

<!DOCTYPE html>
<html lang="zh">
<head><meta charset="UTF-8" /><meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta http-equiv="X-UA-Compatible" content="ie=edge" /><title>Document</title>
</head>
<body><div class="box" contenteditable  style="border: 1px solid red;">我是可编辑的div</div><button onclick="pasteHtmlAtCaret('我是插入的内容')">插入</button>
</body>
<script type="text/javascript">function pasteHtmlAtCaret(html) {var sel, range;if (window.getSelection) {// IE9 and non-IEsel = window.getSelection();if (sel.getRangeAt && sel.rangeCount) {range = sel.getRangeAt(0);range.deleteContents();// Range.createContextualFragment() would be useful here but is// only relatively recently standardized and is not supported in// some browsers (IE9, for one)var el = document.createElement("div");el.innerHTML = html;var frag = document.createDocumentFragment(), node, lastNode;while ( (node = el.firstChild) ) {lastNode = frag.appendChild(node);}range.insertNode(frag);// Preserve the selectionif (lastNode) {range = range.cloneRange();range.setStartAfter(lastNode);range.collapse(true);sel.removeAllRanges();sel.addRange(range);}}} else if (document.selection && document.selection.type != "Control") {// IE < 9document.selection.createRange().pasteHTML(html);}
}
</script>
</html>

方法二：可插入一段html字符串，可被解析

 <body><div id="box" contentEditable>我是p标签的内容</div></body><script type="text/javascript">document.getElementById("box").onmouseup = function() {insertHtmlAtCursor("<strong>666</strong>")}//插入一个HTML字符串：function insertHtmlAtCursor(html) {var range, node;range = window.getSelection().getRangeAt(0);node = range.createContextualFragment(html);range.insertNode(node);}</script>

方法三： 插入一段文本

 <body><div id="box" contentEditable>我是p标签的内容</div></body><script type="text/javascript">document.getElementById("box").onmouseup = function() {insertTextAtCursor("<strong>666</strong>")}function insertTextAtCursor(txt) {var sel = window.getSelection();var iEnd = sel.anchorOffset;var htmldata = sel.anchorNode.data;if(htmldata) {var finaldata = htmldata.substring(0, iEnd) + txt + htmldata.substring(iEnd);sel.anchorNode.textContent = finaldata} else {sel.anchorNode.textContent = txt}}</script>

方法四： 插入一个节点

 <body><div id="box" contentEditable>我是p标签的内容</div></body><script type="text/javascript">document.getElementById("box").onmouseup = function() {insertTextAtCursor("<strong>666</strong>")}function insertTextAtCursor(text) {var sel = window.getSelection();if(sel.getRangeAt && sel.rangeCount) {var range = sel.getRangeAt(0);range.deleteContents();range.insertNode(document.createTextNode(text));}}</script>

总结了以上方式，大概能满足你插入的基本需求了

获取光标位置：

 console.log(window.getSelection().anchorOffset)  //起始点位置console.log(window.getSelection().focusOffset)   //末尾点位置

获取选中区域的文本：

document.onmouseup=function(){console.log(window.getSelection().toString())
}

光标移动到最后：

 <body><div id="box" contentEditable>我是p标签的内容</div></body><script type="text/javascript">document.getElementById("box").onmouseup = function() {set_focus(this)}//光标移动到最后function set_focus(el) {//   el.focus();//创建一个range范围对象var range = document.createRange();//用于设置 Range，使其包含一个 Node的内容。range.selectNodeContents(el);//将包含着的这段内容的光标设置到最后去，true 折叠到 Range 的 start 节点，false 折叠到 end 节点。如果省略，则默认为 false .range.collapse(false);var sel = window.getSelection();sel.removeAllRanges();sel.addRange(range);}</script>

记录光标和恢复光标：`通过一个例子演示`

 <body><div id="box" contentEditable>我是p标签的内容</div><button id="saveBtn">记录光标位置</button><button id="restoreBtn">恢复光标位置</button></body><script type="text/javascript">//全局变量用来存放range变量，恢复的时候使用let range = nulldocument.getElementById("saveBtn").onclick=function(){range = saveSelection()}document.getElementById("restoreBtn").onclick=function(){restoreSelection(range)}function saveSelection() {if(window.getSelection) {sel = window.getSelection();if(sel.getRangeAt && sel.rangeCount) {return sel.getRangeAt(0);}} else if(document.selection && document.selection.createRange) {return document.selection.createRange();}return null;}function restoreSelection(range) {if(range) {if(window.getSelection) {sel = window.getSelection();sel.removeAllRanges();sel.addRange(range);} else if(document.selection && range.select) {range.select();}}}</script>

先这么多，有新的需求或者想起来再补