interface类型的变量,​变量 param 被声明为类型为 AnimateCallback 的变量

export interface AnimateCallback { 
  finish: (isPush: boolean, isExit: boolean) => void; 
  start: (isPush: boolean, isExit: boolean) => void; 
  onFinish: (isPush: boolean, isExit: boolean) => void 
  timeout: number; 
} 
 
export class CustomTransition { 
  registerNavParam(name: string, startCallback: (operation: boolean, isExit: boolean) => void, 
                   endCallback:(operation: boolean, isExit: boolean) => void, 
                   onFinish: (opeation: boolean, isExit: boolean) => void, timeout: number): void { 
 
    if (customTransitionMap.has(name)) { 
      let param : AnimateCallback  = customTransitionMap.get(name); 
      param.start = startCallback; 
      param.finish = endCallback; 
      param.timeout = timeout; 
      param.onFinish = onFinish; 
      return; 
    } 
    let params: AnimateCallback = {timeout: timeout, start: startCallback, finish: endCallback, onFinish: onFinish}; 
    customTransitionMap.set(name, params); 
  } 
}