let 和 var的区别 答:不同点在于作用域 1.(全局下)首先 let关键字声明的变量是这样写会导致错误. let声明的变量类似于”本地变量“,函数内如何不重新声明,还是会被改变 var a =10; var a ="10a"; let b =20; let b ="20b"; console.log(a);//10a console.log(b);//报错 Identifier 'b' has already been declared 2.(方法内)…
一.Cookie,Session,Token简介 # 这三者都解决了HTTP协议无状态的问题 session ID or session token is a piece of data that is used in network communications (often over HTTP) to identify a session, a series of related message exchanges. Session identifiers become necessary…