countdown.js:156 Uncaught TypeError: Cannot read property 'length' of undefined ? ?at renderDigit (countdown.js:156) ? ?at render (countdown.js:132) ? ?at countdown.js:24 ?允許的時(shí)候報(bào)錯(cuò) ?說 法讀取定義的屬性的“長度” 就是數(shù)組那邊的長度報(bào)錯(cuò)。什么原因？