js報錯Cannot read property 'length' of undefined

網上找到的答案：js報錯Cannot read property 'length' of undefined時一般是傳入的參數是undefined

我原來的代碼是

objTmp = document.getElementById("cke_txtKldgAnswer");
            if (objTmp.value.length == 0) {
                inputChkFail('<br><span class="f14 clLRed">提示：請填寫標題!</span>');
                return false;
            } else {
                objTmp.value = TrmEgMark(objTmp.value.Trim());
            }

由於txtKldgAnswer被替換成CKEDITOR.replace('txtKldgAnswer', { height: '500px', width: '99%' });

cke_txtKldgAnswer是CKEDITOR運行后生成div的id,在運行之前是沒有的,

document.getElementById("cke_txtKldgAnswer")應該是檢測不到元素，於是報錯。

解決辦法：

 if (CKEDITOR.instances.txtKldgAnswer.getData() == "") {
                inputChkFail('<br><span class="f14 clLRed">提示：請填寫答案!</span>');
                return false;
            } else {
                objTmp.value = TrmEgMark(objTmp.value.Trim());
            }