報錯：for..in loops iterate over the entire prototype chain, which is virtually never what you want.

for..in loops iterate over the entire prototype chain, which is virtually never what you want. 

意思是使用for..in會遍歷整個原型鏈，這樣不是很好的實現方法，推薦使用Object.keys
————————————————
版權聲明：本文為CSDN博主「咕嚕咕嚕的車輪向前」的原創文章，遵循CC 4.0 BY-SA版權協議，轉載請附上原文出處鏈接及本聲明。
原文鏈接：https://blog.csdn.net/zhongmei121/article/details/105536527