fix(toggle): handle falsy input as expected (#82)

Co-authored-by: Alec Larson <1925840+aleclarson@users.noreply.github.com>

src/array/toggle.ts

@@ -30,25 +30,22 @@ export function toggle<T>(
     strategy?: 'prepend' | 'append'
   },
 ): T[] {
-  if (!array && !item) {
-    return []
-  }
   if (!array) {
-    return [item]
+    return item !== undefined ? [item] : []
   }
-  if (!item) {
+  if (item === undefined) {
     return [...array]
   }
+
   const matcher = toKey
     ? (x: T, idx: number) => toKey(x, idx) === toKey(item, idx)
     : (x: T) => x === item
+
   const existing = array.find(matcher)
-  if (existing) {
+
+  if (existing !== undefined) {
     return array.filter((x, idx) => !matcher(x, idx))
   }
-  const strategy = options?.strategy ?? 'append'
-  if (strategy === 'append') {
-    return [...array, item]
-  }
-  return [item, ...array]
+
+  return options?.strategy === 'prepend' ? [item, ...array] : [...array, item]
 }

tests/array/toggle.test.ts

@@ -4,15 +4,13 @@ const cast = <T = any[]>(value: any): T => value
 
 describe('toggle', () => {
   test('should handle null input list', () => {
-    const result = _.toggle(cast(null), 'a')
+    let result = _.toggle(cast(null), 'a')
     expect(result).toEqual(['a'])
-  })
-  test('should handle null input list and null item', () => {
-    const result = _.toggle(cast(null), null)
+    result = _.toggle(cast(null), undefined)
     expect(result).toEqual([])
   })
-  test('should handle null item', () => {
-    const result = _.toggle(['a'], null)
+  test('should skip undefined item', () => {
+    const result = _.toggle(['a'], undefined)
     expect(result).toEqual(['a'])
   })
   test('should add item when it does not exist using default matcher', () => {
@@ -39,4 +37,11 @@ describe('toggle', () => {
     const result = _.toggle(['a'], 'b', null, { strategy: 'prepend' })
     expect(result).toEqual(['b', 'a'])
   })
+  test('should work with falsy values', () => {
+    expect(_.toggle([1, 2], 0)).toEqual([1, 2, 0])
+
+    expect(_.toggle([1, 0, 2], 0)).toEqual([1, 2])
+
+    expect(_.toggle([1, 2], null)).toEqual([1, 2, null])
+  })
 })