jQuery Cannot set “selected”=“selected” via attr() on elements?

Question

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$(\'.test\').         


        

Answer 1

The selected attribute does not correspond to the current selectedness state of the option. The selected attribute corresponds to the default selectedness, which will be restored if .reset() is called (or a type="reset" button is clicked) on the form. The current selectedness state can be accessed using the DOM property selected, whereas the default-selectedness, as reflected by the attribute, is accessed under the DOM property defaultSelected.

The same goes for value vs defaultValue on /</code>, and <code>checked</code>/<code>defaultChecked</code> on <code>type="checkbox"</code>/<code>"radio"</code>.</p> <p>jQuery's <code>attr()</code> is misleadingly named, and its attempts to pretend attributes and properties are the same thing is flawed. When you use <code>attr()</code>, you are usually accessing the property, <em>not</em> the attribute. Consequently, <code>$(el).attr('selected', 'selected')</code> is actually doing <code>el.selected= 'selected'</code>. This works because <code>'selected'</code>, as with any non-empty string, is ‘truthy’: it gets converted to <code>el.selected= true</code>. But this does not at any point touch the <code>selected="selected"</code> attribute.</p> <p>IE further complicates this already confusing situation by (a) getting <code>getAttribute</code>/<code>setAttribute</code> wrong so it accesses the properties instead of the attributes (which is why you should never use these methods in an HTML document), and (b) incorrectly mapping the current form state to the HTML attributes, so the attributes do actually appear in that browser.</p> <blockquote> <p>but I need selected="selected" there</p> </blockquote> <p>Why? Are you serialising the form to <code>innerHTML</code>? This won't include form field values (again, except in IE due to the bug), so is not a usable way to store field values.</p> </p> <div class="appendcontent"> </div> </div> <div class="jieda-reply"> <span class="jieda-zan button_agree" type="zan" data-id='861818'> <i class="iconfont icon-zan"></i> <em>0</em> </span> <span type="reply" class="showpinglun" data-id="861818"> <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-251862.html"> 查看其它3个回答 </a> </div></center> </div> </div> <div class="comments-mod " style="display: none; float:none;padding-top:10px;" id="comment_861818"> <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="861818">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="251862" id="ans_qid" name="qid"> <input type="hidden" id="tokenkey" name="tokenkey" value=''/> <input type="hidden" value="jQuery Cannot set “selected”=“selected” via attr() on <option> elements?" 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="251862" 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-->