如何在Angular2 Typescript中返回多个值

Question

在md-table中实现过滤器和分页功能时，我试图在打字稿中返回多个值。当我运行代码时，出现错误“无法访问代码”。

 return Observable.merge(...displayPatientDataChanges).map(() => {
   const startIndex = this._paginator.pageIndex * this._paginator.pageSize;
   const data = this._patientDatabase.data.slice();
   return data.splice(startIndex, this._paginator.pageSize);

 // I get the error here on the second return function
   return this._patientDatabase.data.slice().filter((item: Patient) => {
     let searchStr = (item.firstname + item.lastname).toLowerCase();
     return searchStr.indexOf(this.filter.toLowerCase()) != -1;
   });

 });
}

disconnect() {}

Answer 1

那是因为这些方法在到达以下位置后结束：

return data.splice(startIndex, this._paginator.pageSize);

这意味着永远不会到达以下代码，因此会出现错误Unreachable code detected：

return this._patientDatabase.data.slice().filter((item: Patient) => {
     let searchStr = (item.firstname + item.lastname).toLowerCase();
     return searchStr.indexOf(this.filter.toLowerCase()) != -1;
});

如果您想返回两个值，则需要返回一个数组或对象：

const something1 = data.splice(startIndex, this._paginator.pageSize);
const something2 = this._patientDatabase.data.slice().filter((item: Patient) => {
     let searchStr = (item.firstname + item.lastname).toLowerCase();
     return searchStr.indexOf(this.filter.toLowerCase()) != -1;
});
return [something1, something2] // or {something1, something2}