转载--闭包

感谢--https://blog.csdn.net/qq_40776187/article/details/86738851?spm=1001.2101.3001.6650.2&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-2.pc_relevant_aa&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-2.pc_relevant_aa&utm_relevant_index=5