Improve readibility of format normalization

packages/dataviews/src/types/field-api.ts

@@ -325,15 +325,17 @@ export type Field< Item > = {
  */
 type FormatDate = {
 	date?: string;
-	weekStartsOn?:
-		| 'sunday'
-		| 'monday'
-		| 'tuesday'
-		| 'wednesday'
-		| 'thursday'
-		| 'friday'
-		| 'saturday';
+	weekStartsOn?: DayString;
 };
+export type DayNumber = 0 | 1 | 2 | 3 | 4 | 5 | 6;
+export type DayString =
+	| 'sunday'
+	| 'monday'
+	| 'tuesday'
+	| 'wednesday'
+	| 'thursday'
+	| 'friday'
+	| 'saturday';
 
 export type NormalizedField< Item > = Omit< Field< Item >, 'Edit' > & {
 	label: string;

packages/dataviews/src/utils/normalize-fields.ts

@@ -13,6 +13,7 @@ import { getSettings } from '@wordpress/date';
  */
 import getFieldTypeDefinition from '../field-types';
 import type {
+	DayString,
 	DataViewRenderFieldProps,
 	Field,
 	FieldTypeDefinition,
@@ -26,7 +27,7 @@ import {
 	SINGLE_SELECTION_OPERATORS,
 } from '../constants';
 import hasElements from './has-elements';
-import { numberToWeekStartsOn } from './week-starts-on';
+import { numberToWeekStartsOn, DAYS_OF_WEEK } from './week-starts-on';
 
 const getValueFromId =
 	( id: string ) =>
@@ -188,22 +189,21 @@ export default function normalizeFields< Item >(
 
 		const filterBy = getFilterBy( field, fieldTypeDefinition );
 
-		const format =
-			field.type === 'date'
-				? {
-						date:
-							field.format?.date !== undefined &&
-							typeof field.format.date === 'string'
-								? field.format.date
-								: getSettings().formats.date,
-						weekStartsOn:
-							field.format?.weekStartsOn !== undefined
-								? field.format.weekStartsOn
-								: numberToWeekStartsOn(
-										getSettings().l10n.startOfWeek
-								  ),
-				  }
-				: {};
+		let format = {};
+		if ( field.type === 'date' ) {
+			format = {
+				date:
+					field.format?.date !== undefined &&
+					typeof field.format.date === 'string'
+						? field.format.date
+						: getSettings().formats.date,
+				weekStartsOn: DAYS_OF_WEEK.includes(
+					field.format?.weekStartsOn as DayString
+				)
+					? field?.format?.weekStartsOn
+					: numberToWeekStartsOn( getSettings().l10n.startOfWeek ),
+			};
+		}
 
 		return {
 			...field,

packages/dataviews/src/utils/week-starts-on.ts

@@ -1,13 +1,9 @@
-type DayNumber = 0 | 1 | 2 | 3 | 4 | 5 | 6;
-type DayString =
-	| 'sunday'
-	| 'monday'
-	| 'tuesday'
-	| 'wednesday'
-	| 'thursday'
-	| 'friday'
-	| 'saturday';
-const days: DayString[] = [
+/**
+ * Internal dependencies
+ */
+import type { DayNumber, DayString } from '../types/field-api';
+
+export const DAYS_OF_WEEK: DayString[] = [
 	'sunday',
 	'monday',
 	'tuesday',
@@ -26,7 +22,7 @@ const DEFAULT_DAY_NUMBER = 0;
  * @return The corresponding number (0 for Sunday, 1 for Monday, etc.)
  */
 export function weekStartsOnToNumber( day: DayString ): DayNumber {
-	const index = days.indexOf( day );
+	const index = DAYS_OF_WEEK.indexOf( day );
 	if ( index === -1 ) {
 		return DEFAULT_DAY_NUMBER;
 	}
@@ -41,7 +37,7 @@ export function weekStartsOnToNumber( day: DayString ): DayNumber {
  * @return The corresponding day name ('sunday', 'monday', etc.)
  */
 export function numberToWeekStartsOn( day: DayNumber ): DayString {
-	const result = days[ day ];
+	const result = DAYS_OF_WEEK[ day ];
 	if ( result === undefined ) {
 		return DEFAULT_DAY_STRING;
 	}