type-being-props-selector.md

Type Being Props Selector

Type Definition

interface IMonthProps {
  startMonthId: string;
  endMonthId: string;

  startMonthName: string;
  endMonthName: string;

  startMonthSymbol: string;
  endMonthSymbol: string;
}

type IMonthRange<T = false> = T extends Array<infer F>
  ? {
    [k in (
      | (F extends 'id' ? keyof Pick<IMonthProps, 'startMonthId' | 'endMonthId'> : never)
      | (F extends 'name' ? keyof Pick<IMonthProps, 'startMonthName' | 'endMonthName'> : never)
      | (F extends 'symbol' ? keyof Pick<IMonthProps, 'startMonthSymbol' | 'endMonthSymbol'> : never)
    )]: string;
  }
  : IMonthProps;

Use of the Type

Usage	Inherited Fields
IMonthRange	startMonthId, endMonthId, startMonthName, endMonthName, startMonthSymbol and endMonthSymbol
IMonthRange<['name']>	startMonthName and endMonthName
IMonthRange<['symbol', 'id']>	startMonthSymbol, endMonthSymbol, startMonthId and endMonthId

• inherit all fields of IMonthProps

interface IAcademicYear extends IMonthRange {
  year: number;
}

const academicYear: IAcademicYear = {
  year: 2020,
  startMonthId: '9',
  endMonthId: '6',
  startMonthName: 'September',
  endMonthName: 'June',
  startMonthSymbol: 'Sep',
  endMonthSymbol: 'Jun'
}

• inherit *MonthName and *MonthSymbol fields of IMonthProps

interface IAcademicYear extends IMonthRange<['name', 'symbol']> {
  year: number;
}

const academicYear: IAcademicYear = {
  year: 2020,
  startMonthName: 'September',
  endMonthName: 'June',
  startMonthSymbol: 'Sep',
  endMonthSymbol: 'Jun'
}

• inherit *MonthId fields of IMonthProps

const fullYear: IMonthRange<['id']> = {
  startMonthId: '1',
  endMonthId: '12'
};