网上找到的答案：js报错Cannot read property ‘length‘ of undefined时一般是传入的参数是undefined
我原来的代码是
objTmp = document.getElementById("cke_txtKldgAnswer"); if (objTmp.value.length == 0) { inputChkFail(‘<br><span class="f14 clLRed">提示：请填写标题!</span>‘); return false; } else { objTmp.value = TrmEgMark(objTmp.value.Trim()); }
由于txtKldgAnswer被替换成CKEDITOR.replace(‘txtKldgAnswer‘, { height: ‘500px‘, width: ‘99%‘ });
cke_txtKldgAnswer是CKEDITOR运行后生成div的id,在运行之前是没有的,
document.getElementById("cke_txtKldgAnswer")应该是检测不到元素，于是报错。
解决办法：
if (CKEDITOR.instances.txtKldgAnswer.getData() == "") { inputChkFail(‘<br><span class="f14 clLRed">提示：请填写答案!</span>‘); return false; } else { objTmp.value = TrmEgMark(objTmp.value.Trim()); }
js报错Cannot read property 'length' of undefined
原文：https://www.cnblogs.com/lianyiu/p/13182751.html