How to get the caret column (not pixels) position in a textarea, in characters, from the start?

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How do you get the caret position in a </code> using JavaScript?</p> <p>For example: <code>This is| a text</code></p> <p>This should return <code>7</ <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-5408099190056760" data-ad-slot="7305827575" data-ad-format="auto" data-full-width-responsive="true"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div> <div class="relativetags"> 相关标签: </div> </div> <div class="fly-panel detail-box" id="flyReply"> <fieldset class="layui-elem-field layui-field-title" style="text-align: center;"> <legend>4条回答</legend> </fieldset> <ul class="jieda" id="jieda"> <li data-id="111"> <a name="item-1111111111"></a> <div class="detail-about detail-about-reply"> <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-29.html"> <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000029.jpg" alt=" "> </a> <div class="fly-detail-user"> <a href="https://www.e-learn.cn/qa/u-29.html" class="fly-link"> <cite>甜味超标 </cite> </a> </div> <div class="detail-hits"> <span>2020-11-21 07:15</span> </div> </div> <div class="detail-body jieda-body photos"> <p><strong>Updated 5 September 2010</strong></p> <p>Seeing as everyone seems to get directed here for this issue, I'm adding my answer to a similar question, which contains the same code as this answer but with full background for those who are interested:</p> <p>IE's document.selection.createRange doesn't include leading or trailing blank lines</p> <p>To account for trailing line breaks is tricky in IE, and I haven't seen any solution that does this correctly, including any other answers to this question. It is possible, however, using the following function, which will return you the start and end of the selection (which are the same in the case of a caret) within a <code><textarea></code> or text <code><input></code>.</p> <p>Note that the textarea must have focus for this function to work properly in IE. If in doubt, call the textarea's <code>focus()</code> method first.</p> <pre><code>function getInputSelection(el) { var start = 0, end = 0, normalizedValue, range, textInputRange, len, endRange; if (typeof el.selectionStart == "number" && typeof el.selectionEnd == "number") { start = el.selectionStart; end = el.selectionEnd; } else { range = document.selection.createRange(); if (range && range.parentElement() == el) { len = el.value.length; normalizedValue = el.value.replace(/\r\n/g, "\n"); // Create a working TextRange that lives only in the input textInputRange = el.createTextRange(); textInputRange.moveToBookmark(range.getBookmark()); // Check if the start and end of the selection are at the very end // of the input, since moveStart/moveEnd doesn't return what we want // in those cases endRange = el.createTextRange(); endRange.collapse(false); if (textInputRange.compareEndPoints("StartToEnd", endRange) > -1) { start = end = len; } else { start = -textInputRange.moveStart("character", -len); start += normalizedValue.slice(0, start).split("\n").length - 1; if (textInputRange.compareEndPoints("EndToEnd", endRange) > -1) { end = len; } else { end = -textInputRange.moveEnd("character", -len); end += normalizedValue.slice(0, end).split("\n").length - 1; } } } } return { start: start, end: end }; } </code></pre> <div class="appendcontent"> </div> </div> <div class="jieda-reply"> <span class="jieda-zan button_agree" type="zan" data-id='27937'> <i class="iconfont icon-zan"></i> <em>0</em> </span> <span type="reply" class="showpinglun" data-id="27937"> <i class="iconfont icon-svgmoban53"></i> 讨论(0) </span> <div class="jieda-admin"> </div> </div> <div class="comments-mod " style="display: none; float:none;padding-top:10px;" id="comment_27937"> <div class="areabox clearfix"> <form class="layui-form" action=""> <div class="layui-form-item"> <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label> <div class="layui-input-block" style="margin-left:90px;"> <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" /> <input type='hidden' value='0' name='replyauthor' /> </div> <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="27937">提交评论 </span></div> </div> </form> </div> <hr> <ul class="my-comments-list nav"> <li class="loading"> <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' /> 加载中... </li> </ul> </div> </li> <li data-id="111"> <a name="item-1111111111"></a> <div class="detail-about detail-about-reply"> <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-75.html"> <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000075.jpg" alt=" "> </a> <div class="fly-detail-user"> <a href="https://www.e-learn.cn/qa/u-75.html" class="fly-link"> <cite>野性不改 </cite> </a> </div> <div class="detail-hits"> <span>2020-11-21 07:23</span> </div> </div> <div class="detail-body jieda-body photos"> <p>I modified the above function to account for carriage returns in IE. It's untested but I did something similar with it in my code so it should be workable.</p> <pre><code>function getCaret(el) { if (el.selectionStart) { return el.selectionStart; } else if (document.selection) { el.focus(); var r = document.selection.createRange(); if (r == null) { return 0; } var re = el.createTextRange(), rc = re.duplicate(); re.moveToBookmark(r.getBookmark()); rc.setEndPoint('EndToStart', re); var add_newlines = 0; for (var i=0; i<rc.text.length; i++) { if (rc.text.substr(i, 2) == '\r\n') { add_newlines += 2; i++; } } //return rc.text.length + add_newlines; //We need to substract the no. of lines return rc.text.length - add_newlines; } return 0; } </code></pre> <div class="appendcontent"> </div> </div> <div class="jieda-reply"> <span class="jieda-zan button_agree" type="zan" data-id='27938'> <i class="iconfont icon-zan"></i> <em>0</em> </span> <span type="reply" class="showpinglun" data-id="27938"> <i class="iconfont icon-svgmoban53"></i> 讨论(0) </span> <div class="jieda-admin"> </div> </div> <div class="comments-mod " style="display: none; float:none;padding-top:10px;" id="comment_27938"> <div class="areabox clearfix"> <form class="layui-form" action=""> <div class="layui-form-item"> <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label> <div class="layui-input-block" style="margin-left:90px;"> <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" /> <input type='hidden' value='0' name='replyauthor' /> </div> <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="27938">提交评论 </span></div> </div> </form> </div> <hr> <ul class="my-comments-list nav"> <li class="loading"> <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' /> 加载中... </li> </ul> </div> </li> <li data-id="111"> <a name="item-1111111111"></a> <div class="detail-about detail-about-reply"> <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-56.html"> <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000056.jpg" alt=" "> </a> <div class="fly-detail-user"> <a href="https://www.e-learn.cn/qa/u-56.html" class="fly-link"> <cite>遇见更好的自我 </cite> </a> </div> <div class="detail-hits"> <span>2020-11-21 07:32</span> </div> </div> <div class="detail-body jieda-body photos"> <p>With Firefox, Safari (and other Gecko based browsers) you can easily use textarea.selectionStart, but for IE that doesn't work, so you will have to do something like this:</p> <pre><code>function getCaret(node) { if (node.selectionStart) { return node.selectionStart; } else if (!document.selection) { return 0; } var c = "\001", sel = document.selection.createRange(), dul = sel.duplicate(), len = 0; dul.moveToElementText(node); sel.text = c; len = dul.text.indexOf(c); sel.moveStart('character',-1); sel.text = ""; return len; } </code></pre> <p>(complete code here)</p> <p>I also recommend you to check the jQuery FieldSelection Plugin, it allows you to do that and much more...</p> <p><strong>Edit:</strong> I actually re-implemented the above code: </p> <pre><code>function getCaret(el) { if (el.selectionStart) { return el.selectionStart; } else if (document.selection) { el.focus(); var r = document.selection.createRange(); if (r == null) { return 0; } var re = el.createTextRange(), rc = re.duplicate(); re.moveToBookmark(r.getBookmark()); rc.setEndPoint('EndToStart', re); return rc.text.length; } return 0; } </code></pre> <p>Check an example here.</p> <div class="appendcontent"> </div> </div> <div class="jieda-reply"> <span class="jieda-zan button_agree" type="zan" data-id='27936'> <i class="iconfont icon-zan"></i> <em>0</em> </span> <span type="reply" class="showpinglun" data-id="27936"> <i class="iconfont icon-svgmoban53"></i> 讨论(0) </span> <div class="jieda-admin"> </div> </div> <div class="comments-mod " style="display: none; float:none;padding-top:10px;" id="comment_27936"> <div class="areabox clearfix"> <form class="layui-form" action=""> <div class="layui-form-item"> <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label> <div class="layui-input-block" style="margin-left:90px;"> <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" /> <input type='hidden' value='0' name='replyauthor' /> </div> <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="27936">提交评论 </span></div> </div> </form> </div> <hr> <ul class="my-comments-list nav"> <li class="loading"> <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' /> 加载中... </li> </ul> </div> </li> <li data-id="111"> <a name="item-1111111111"></a> <div class="detail-about detail-about-reply"> <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-19.html"> <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000019.jpg" alt=" "> </a> <div class="fly-detail-user"> <a href="https://www.e-learn.cn/qa/u-19.html" class="fly-link"> <cite>野趣味 </cite> </a> </div> <div class="detail-hits"> <span>2020-11-21 07:34</span> </div> </div> <div class="detail-body jieda-body photos"> <p>If you don't have to support IE, you can use <code>selectionStart</code> and <code>selectionEnd</code> attributes of <code>textarea</code>.</p> <p>To get caret position just use <code>selectionStart</code>:</p> <pre><code>function getCaretPosition(textarea) { return textarea.selectionStart } </code></pre> <p>To get the strings surrounding the selection, use following code:</p> <pre><code>function getSurroundingSelection(textarea) { return [textarea.value.substring(0, textarea.selectionStart) ,textarea.value.substring(textarea.selectionStart, textarea.selectionEnd) ,textarea.value.substring(textarea.selectionEnd, textarea.value.length)] } </code></pre> <p>Demo on JSFiddle.</p> <p>See also HTMLTextAreaElement docs.</p> <div class="appendcontent"> </div> </div> <div class="jieda-reply"> <span class="jieda-zan button_agree" type="zan" data-id='27939'> <i class="iconfont icon-zan"></i> <em>0</em> </span> <span type="reply" class="showpinglun" data-id="27939"> <i class="iconfont icon-svgmoban53"></i> 讨论(0) </span> <div class="jieda-admin"> </div> </div> <div class="comments-mod " style="display: none; float:none;padding-top:10px;" id="comment_27939"> <div class="areabox clearfix"> <form class="layui-form" action=""> <div class="layui-form-item"> <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label> <div class="layui-input-block" style="margin-left:90px;"> <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" /> <input type='hidden' value='0' name='replyauthor' /> </div> <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="27939">提交评论 </span></div> </div> </form> </div> <hr> <ul class="my-comments-list nav"> <li class="loading"> <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' /> 加载中... </li> </ul> </div> </li> <style> .laypage-main a, .laypage-main span { display: inline-block; } </style> </ul> <div class="layui-form layui-form-pane"> <form id="huidaform" name="answerForm" method="post"> <div class="layui-form-item layui-form-text"> <a name="comment"></a> <div class="layui-input-block"> <script type="text/javascript" src="https://www.e-learn.cn/qa/static/js/neweditor/ueditor.config.js"></script> <script type="text/javascript" src="https://www.e-learn.cn/qa/static/js/neweditor/ueditor.all.js"></script> <script type="text/plain" id="editor" name="content" style="width:100%;height:200px;"></script> <script type="text/javascript"> var isueditor=1; 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