JS Closure

记载一下看的链接

MDN上 Closure定义：

A closure is the combination of a function and the lexical environment within which that function was declared. 

https://www.cnblogs.com/huangxincheng/p/4189843.html?utm_source=qq&utm_medium=social&utm_oi=599727082251751424

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Closures

https://stackoverflow.com/questions/111102/how-do-javascript-closures-work