better-scroll  is referenced in   typescript , the code is as follows 
import * as BScroll from "better-scroll"
...
console.log(BScroll)
new BScroll(".wrapper")
...console output
{default: , __esModule: true}
> default: BScroll(el, options)
  __esModule:true
> __proto__:Object
> Uncaught TypeError: BScroll is not a constructor
... check the author  package.json   types  declare no problem 
...
  "types": "./types/index.d.ts",
... check the author  * .d.ts  No problem 
...
declare const BScroll: BScrollStatic;
declare module "better-scroll" {
  export = BScroll;
}
...ask for help, what"s wrong with me here?
