预期在react中的箭头函数末尾返回一个值

Question

I get the warning in the title when compiling. I understand that it is about not handling some cases of if , but how can I filter before mapping in the correct way?

    componentDidMount() {
        this.props.UserReducer.user.employeeInfoList.map(role => {
          if (role.employeeType) this.rolesOfUser.push(role.employeeType);

          if (role.xdockId) this.xdockIdsOfUser.push(role.xdockId);
        });

  }

Answer 1

It is because you are misusing map which is used for mapping/transforming one array to another. Having a call to map without a return value indicates a problem, as you shouldn't be using it to just iterate over an array performing some action.

It looks like what you really wanted was a forEach call.

Answer 2

To filter an array use Array#filter . Also you can use Array#forEach for your case

componentDidMount() {
    this.props.UserReducer.user.employeeInfoList.forEach(role => {
      if (role.employeeType) this.rolesOfUser.push(role.employeeType);

      if (role.xdockId) this.xdockIdsOfUser.push(role.xdockId);
    });
}

Or

componentDidMount() {
  const rolesOfUser = this.props.UserReducer.user.employeeInfoList.filter(role => {
    return role.employeeType;
  })

  const xdockIdsOfUser = this.props.UserReducer.user.employeeInfoList.filter(role => {
    return role.xdockId;
  })

  // Do smth with both arrays
}