获取不到元素，获取值为null

Question

问题描述

图片描述
图片描述

问题出现的环境背景及自己尝试过哪些方法

报错元素为“null”，但是cname却能获取。报错是什么意思？
尝试过吧引用的js文件都放到下面执行也不行

相关代码

前端页面

<div class="modal-body">
                    <ul id="BranchType" class="nav nav-tabs">
                        <li class="active" id="applyMergeLi  ">
                            <a id="applyMergeA" href="#ApplyMerge" onclick=setCookieApplyMerge() data-toggle="tab">申请合入</a>
                        </li>
                        <li  id="applyPublishLi " class="active1" >
                            <a id="applyPublisA" href="#ApplyPublish" onclick=setCookieApplyPublish() data-toggle="tab">申请发布</a>
                            </li>
                        <li  id="mergeReviewLogLi" class="active2">
                            <a id="mergeReviewLogA" href="#MergeReviewLog" onclick=setCookieMergeReviewLog() data-toggle="tab">合入审批记录</a>
                        </li>
                        <li  id="publishReviewLogLi" class="active3" >
                            <a id="publishReviewLogA" href="#PublishReviewLog" onclick=setCookiePublishReviewLog() data-toggle="tab">发布审批记录</a>
                        </li>
                    </ul>
                    </div>

<div 方法定义部分 common.js>
function hasClass( elementOne,cName )
{
    if (elementOne.className==null){
        return false;
    }
    return !!elementOne.className.match( new RegExp( "(\\s|^)" + cName + "(\\s|$)") ); // ( \\s|^ ) 判断前面是否有空格 （\\s | $ ）判断后面是否有空格 两个感叹号为转换为布尔值 以方便做判断
}

function addClass( elementOne,cName )
{
    if( !hasClass( elementOne,cName ) ){
        elementOne.className += " " + cName;
    };
}

function removeClass( elementOne,cName )
{
    if( hasClass( elementOne,cName ) ){
        elementOne.className = elementOne.className.replace( new RegExp( "(\\s|^)" + cName + "(\\s|$)" )," " ); // replace方法是替换
    };
}

</div>

<div  方法调用部分`请输入代码`>

function onloadApplyPage()
{
    var applyInfoPage = getCookie("applyInfoPage");
    var applyMergeLi = document.getElementById("applyMergeLi");
    var applyPublishLi = document.getElementById("applyPublishLi");
    var mergeReviewLogLi = document.getElementById("mergeReviewLogLi");
    var publishReviewLogLi = document.getElementById("publishReviewLogLi");
    var ApplyMerge = document.getElementById("ApplyMerge");
    var ApplyPublish = document.getElementById("ApplyPublish");
    var MergeReviewLog = document.getElementById("MergeReviewLog");
    var PublishReviewLog = document.getElementById("PublishReviewLog");
    if(applyInfoPage==1)
    {
        //为这个类移除属性
        addClass(applyMergeLi,"active");
        removeClass(applyPublishLi,"active");
        removeClass(mergeReviewLogLi,"active"); 
        removeClass(publishReviewLogLi,"active");         
        $("#applyMergeA").attr("aria-expanded","true");
        $("#applyPublishA").attr("aria-expanded","false");
        $("#mergeReviewLogA").attr("aria-expanded","false");
        $("#publishReviewLogA").attr("aria-expanded","false");
        addClass(ApplyMerge,"active");
        removeClass(ApplyPublish,"active");
        removeClass(MergeReviewLog,"active");
        removeClass(PublishReviewLog,"active");        
    }
    
    if(applyInfoPage==2)
    {
        //为这个类移除属性
        removeClass(applyMergeLi,"active");
        addClass(applyPublishLi,"active");
        removeClass(mergeReviewLogLi,"active"); 
        removeClass(publishReviewLogLi,"active");         
        $("#applyMergeA").attr("aria-expanded","false");
        $("#applyPublishA").attr("aria-expanded","true");
        $("#mergeReviewLogA").attr("aria-expanded","false");
        $("#publishReviewLogA").attr("aria-expanded","false");
        removeClass(ApplyMerge,"active");
        addClass(ApplyPublish,"active");
        removeClass(MergeReviewLog,"active");
        removeClass(PublishReviewLog,"active");         
    }

    if(applyInfoPage==3)
    {
        //为这个类移除属性
        removeClass(applyMergeLi,"active");
        removeClass(applyPublishLi,"active");
        addClass(mergeReviewLogLi,"active"); 
        removeClass(publishReviewLogLi,"active");         
        $("#applyMergeA").attr("aria-expanded","false");
        $("#applyPublishA").attr("aria-expanded","false");
        $("#mergeReviewLogA").attr("aria-expanded","true");
        $("#publishReviewLogA").attr("aria-expanded","false");
        removeClass(ApplyMerge,"active");
        removeClass(ApplyPublish,"active");
        addClass(MergeReviewLog,"active");
        removeClass(PublishReviewLog,"active");
        
    }

    if(applyInfoPage==4)
    {
        //为这个类移除属性
        removeClass(applyMergeLi,"active");
        removeClass(applyPublishLi,"active");
        removeClass(mergeReviewLogLi,"active"); 
        addClass(publishReviewLogLi,"active");         
        $("#applyMergeA").attr("aria-expanded","false");
        $("#applyPublishA").attr("aria-expanded","false");
        $("#mergeReviewLogA").attr("aria-expanded","false");
        $("#publishReviewLogA").attr("aria-expanded","true");
        removeClass(ApplyMerge,"active");
        removeClass(ApplyPublish,"active");
        removeClass(MergeReviewLog,"active");
        addClass(PublishReviewLog,"active");
        
    }
}  


</div>

Answer 1

id属性里为什么有空格？