let 作用域问题 全局变量不能this引用

用let、const定义全局变量name, 用this.name,获取值为空let name = 'dasi'console.log('this---', this.name)console.log('this---', name)打印结果this---this--- dasiconst name = 'dasi'console.log('this---', this.name)console.log('this---', name)打印结果this---this--- dasivar name = 'dasi'console.log('this---', this.name)console.log('this---', name)打印结果this--- dasithis--- dasi