feat: const for priority side + cleanup types

BREAKING CHANGE: bump version to v1.x

README.MD

@@ -96,16 +96,14 @@ const merge = createMerger({
             target[key] += value;
             return target;
         }
-
-        return undefined;
     }
 });
 
 console.log(merge({ a: 1 }, { a: 2 }, { a: 3 }));
 // => { a: 6 }
 ```
 
-Return **undefined** if the default merge behaviour should be used for the current target source pair.
+A returned value indicates that the strategy has been applied.
 
 ## License
 

src/constants.ts

@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2023.
+ * Author Peter Placzek (tada5hi)
+ * For the full copyright and license information,
+ * view the LICENSE file that was distributed with this source code.
+ */
+
+export enum PriorityName {
+    LEFT = 'left',
+    RIGHT = 'right',
+}

src/index.ts

@@ -5,6 +5,7 @@
  * view the LICENSE file that was distributed with this source code.
  */
 
+export * from './constants';
 export * from './module';
 export * from './utils';
 export * from './type';

src/module.ts

@@ -5,7 +5,10 @@
  * view the LICENSE file that was distributed with this source code.
  */
 
-import type { Merger, MergerResult, Options } from './type';
+import { PriorityName } from './constants';
+import type {
+    Merger, MergerResult, Options, OptionsInput,
+} from './type';
 import {
     buildOptions,
     hasOwnProperty,
@@ -39,7 +42,6 @@ export function baseMerger<A extends Record<string, any>, B extends Record<strin
             if (hasOwnProperty(target, key)) {
                 if (options.strategy) {
                     const applied = options.strategy(target, key, source[key]);
-                    // todo: maybe compare returned target and argument passed target
                     if (typeof applied !== 'undefined') {
                         continue;
                     }
@@ -64,12 +66,12 @@ export function baseMerger<A extends Record<string, any>, B extends Record<strin
                     Array.isArray(source[key])
                 ) {
                     switch (options.priority) {
-                        case 'left':
+                        case PriorityName.LEFT:
                             Object.assign(target, {
                                 [key]: mergeArrays(target[key], source[key], options.arrayDistinct),
                             });
                             break;
-                        case 'right':
+                        case PriorityName.RIGHT:
                             Object.assign(target, {
                                 [key]: mergeArrays(source[key], target[key], options.arrayDistinct),
                             });
@@ -79,7 +81,7 @@ export function baseMerger<A extends Record<string, any>, B extends Record<strin
                     continue;
                 }
 
-                if (options.priority === 'right') {
+                if (options.priority === PriorityName.RIGHT) {
                     Object.assign(target, { [key]: source[key] });
                 }
             } else {
@@ -91,7 +93,7 @@ export function baseMerger<A extends Record<string, any>, B extends Record<strin
     return baseMerger(options, target, ...sources);
 }
 
-export function createMerger(input?: Partial<Options>) : Merger {
+export function createMerger(input?: OptionsInput) : Merger {
     const options = buildOptions(input);
 
     return <A extends Record<string, any>, B extends Record<string, any>>(

src/type.ts

@@ -5,6 +5,8 @@
  * view the LICENSE file that was distributed with this source code.
  */
 
+import type { PriorityName } from './constants';
+
 export type MergerResult<A, B> = A extends B ?
     B extends A ?
         // eslint-disable-next-line @typescript-eslint/ban-types
@@ -18,5 +20,7 @@ export type Options = {
     array: boolean,
     arrayDistinct: boolean,
     strategy?: (target: Record<string, any>, key: string, value: unknown) => Record<string, any> | undefined,
-    priority: 'left' | 'right'
+    priority: `${PriorityName}`
 };
+
+export type OptionsInput = Partial<Options>;

src/utils/options.ts

@@ -5,14 +5,15 @@
  * view the LICENSE file that was distributed with this source code.
  */
 
-import type { Options } from '../type';
+import { PriorityName } from '../constants';
+import type { Options, OptionsInput } from '../type';
 
-export function buildOptions(options?: Partial<Options>) {
+export function buildOptions(options?: OptionsInput) : Options {
     options = options || {};
 
     options.array = options.array ?? true;
     options.arrayDistinct = options.arrayDistinct ?? false;
-    options.priority = options.priority || 'left';
+    options.priority = options.priority || PriorityName.LEFT;
 
     return options as Options;
 }