How to decode HTML entities using jQuery?

Question

How do I use jQuery to decode HTML entities in a string?

Answer 1

Without any jQuery:

function decodeEntities(encodedString) {
  var textArea = document.createElement('textarea');
  textArea.innerHTML = encodedString;
  return textArea.value;
}

console.log(decodeEntities('1 & 2')); // '1 & 2'

This works similarly to the accepted answer, but is safe to use with untrusted user input.

---

Security issues in similar approaches

As noted by Mike Samuel, doing this with a

instead of a </code> with untrusted user input is an XSS vulnerability, even if the <code><div></code> is never added to the DOM:</p> <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>function decodeEntities(encodedString) { var div = document.createElement('div'); div.innerHTML = encodedString; return div.textContent; } // Shows an alert decodeEntities('<img src="nonexistent_image" onerror="alert(1337)">')</code></pre> </div> </div> </p> <p>However, this attack is not possible against a <code><textarea></code> because there are no HTML elements that are permitted content of a <textarea>. Consequently, any HTML tags still present in the 'encoded' string will be automatically entity-encoded by the browser.</p> <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>function decodeEntities(encodedString) { var textArea = document.createElement('textarea'); textArea.innerHTML = encodedString; return textArea.value; } // Safe, and returns the correct answer console.log(decodeEntities('<img src="nonexistent_image" onerror="alert(1337)">'))</code></pre> </div> </div> </p> <blockquote> <p><strong>Warning</strong>: Doing this using jQuery's .html() and .val() methods instead of using .innerHTML and <code>.value</code> is also insecure* for some versions of jQuery, <strong>even when using a <code>textarea</code></strong>. This is because older versions of jQuery would deliberately and explicitly evaluate scripts contained in the string passed to <code>.html()</code>. Hence code like this shows an alert in jQuery 1.8:</p> </blockquote> <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false"> <div class="snippet-code"> <pre class="snippet-code-js lang-js prettyprint-override"><code>//<!-- CDATA // Shows alert $("<textarea>") .html("<script>alert(1337);</script>") .text(); //--></code></pre> <pre class="snippet-code-html lang-html prettyprint-override"><code><script src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.3/jquery.min.js"></script></code></pre> </div> </div> </p> <p><sub>* Thanks to Eru Penkman for catching this vulnerability.</sub></p> </p> <div class="appendcontent"> </div> </div> <div class="jieda-reply"> <span class="jieda-zan button_agree" type="zan" data-id='39038'> <i class="iconfont icon-zan"></i> <em>0</em> </span> <span type="reply" class="showpinglun" data-id="39038"> <i class="iconfont icon-svgmoban53"></i> 讨论(0) </span> <div class="jieda-admin"> </div> <div class="noreplaytext bb"> <center><div> <a href="https://www.e-learn.cn/qa/q-16613.html"> 查看其它19个回答 </a> </div></center> </div> </div> <div class="comments-mod " style="display: none; float:none;padding-top:10px;" id="comment_39038"> <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="39038">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> </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; var editor = UE.getEditor('editor',{ //这里可以选择自己需要的工具按钮名称,此处仅选择如下五个 toolbars:[['source','fullscreen', '|', 'undo', 'redo', '|', 'bold', 'italic', 'underline', 'fontborder', 'strikethrough', 'removeformat', 'formatmatch', 'autotypeset', 'blockquote', 'pasteplain', '|', 'forecolor', 'backcolor', 'insertorderedlist', 'insertunorderedlist', 'selectall', 'cleardoc', '|', 'rowspacingtop', 'rowspacingbottom', 'lineheight', '|', 'customstyle', 'paragraph', 'fontfamily', 'fontsize', '|', 'indent', '|', 'justifyleft', 'justifycenter', 'justifyright', 'justifyjustify', '|', 'link', 'unlink', 'anchor', '|', 'simpleupload', 'insertimage', 'scrawl', 'insertvideo', 'attachment', 'map', 'insertcode', '|', 'horizontal', '|', 'preview', 'searchreplace', 'drafts']], initialContent:'', //关闭字数统计 wordCount:false, zIndex:2, //关闭elementPath elementPathEnabled:false, //默认的编辑区域高度 initialFrameHeight:250 //更多其他参数，请参考ueditor.config.js中的配置项 //更多其他参数，请参考ueditor.config.js中的配置项 }); editor.ready(function() { editor.setDisabled(); }); $("#editor").find("*").css("max-width","362px"); </script> </div> </div> <div class="layui-form-item"> <label for="L_vercode" class="layui-form-label">验证码</label> <div class="layui-input-inline"> <input type="text" id="code" name="code" value="" required lay-verify="required" placeholder="图片验证码" autocomplete="off" class="layui-input"> </div> <div class="layui-form-mid"> <span style="color: #c00;"><img class="hand" src="https://www.e-learn.cn/qa/user/code.html" onclick="javascript:updatecode();" id="verifycode"><a class="changecode" href="javascript:updatecode();"> 看不清?</a></span> </div> </div> <div class="layui-form-item"> <input type="hidden" value="16613" id="ans_qid" name="qid"> <input type="hidden" id="tokenkey" name="tokenkey" value=''/> <input type="hidden" value="How to decode HTML entities using jQuery?" id="ans_title" name="title"> <div class="layui-btn layui-btn-disabled" id="ajaxsubmitasnwer" >提交回复</div> </div> </form> </div> </div> <input type="hidden" value="16613" id="adopt_qid" name="qid" /> <input type="hidden" id="adopt_answer" value="0" name="aid" /> </div> <div class="layui-col-md4"> <!-- 热门讨论问题 --> <dl class="fly-panel fly-list-one"> <dt class="fly-panel-title">热议问题</dt> <!-- 本周热门讨论问题显示10条-->