✨ Add product function

docs/api/index.md

@@ -39,6 +39,7 @@
 |  [lte](./lte/) | Returns <code>true</code> if the first argument is less than or equal to the second; otherwise <code>false</code> |
 |  [multiply](./multiply/) | Multiplies first argument and second argument. |
 |  [or](./or/) | Returns true if one or both of its arguments are true; otherwise false. |
+|  [product](./product/) | <b><i>(BETA)</i></b> Multiplies together all the elements of a list. |
 |  [reverse](./reverse/) | Returns a new list or string with the elements or characters in reverse order. |
 |  [startsWith](./startswith/) | Checks if a string starts with the provided substring. |
 |  [subtract](./subtract/) | Subtracts its second argument from its first argument. |

docs/api/product/index.md

@@ -0,0 +1,30 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+
+
+## product variable
+
+> This API is provided as a preview for developers and may change based on feedback that we receive. Do not use this API in a production environment.
+> 
+
+Multiplies together all the elements of a list.
+
+<b>Signature:</b>
+
+```typescript
+product: {
+    (val: number[]): number;
+    (val: bigint[]): bigint;
+}
+```
+
+## Example
+
+
+```ts
+product([1, 2, 3, 4, 5]) // 120
+product([1n, 2n, 3n, 4n, 5n]) //120n
+product([]) // 0
+
+```
+

src/index.ts

@@ -30,6 +30,7 @@ export { lt } from '@/lt'
 export { lte } from '@/lte'
 export { multiply } from '@/multiply'
 export { or } from '@/or'
+export { product } from '@/product'
 export { reverse } from '@/reverse'
 export { startsWith } from '@/startsWith'
 export { subtract } from '@/subtract'

src/product.ts

@@ -0,0 +1,33 @@
+import { first } from '@/first'
+import { isNumber } from '@/isNumber'
+import { isUndefined } from '@/isUndefined'
+import { multiply } from '@/multiply'
+
+/**
+ * Multiplies together all the elements of a list.
+ *
+ * @param val - list An array of numbers
+ * @returns The product of all the numbers in the list
+ *
+ * @example
+ * ```ts
+ * product([1, 2, 3, 4, 5]) // 120
+ * product([1n, 2n, 3n, 4n, 5n]) //120n
+ * product([]) // 0
+ * ```
+ *
+ * @beta
+ */
+const product: {
+  (val: number[]): number
+  (val: bigint[]): bigint
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+} = (val: any) => {
+  const head = first(val) as number | bigint
+  if (isUndefined(head)) return 0
+  const init = isNumber(head) ? 1 : 1n
+
+  return val.reduce(multiply, init)
+}
+
+export { product }

test/product.spec.ts

@@ -0,0 +1,25 @@
+import { product } from '@/product'
+
+describe('product', () => {
+  const tableNumber: [number[], number][] = [
+    [[], 0],
+    [[0, 0], 0],
+    [[1], 1],
+    [[1, 2, 3, 4, 5], 120],
+    [[1, -2, 3, -4, 5], 120]
+  ]
+
+  it.each(tableNumber)('product(%s) -> %s', (val, expected) => {
+    expect(product(val)).toBe(expected)
+  })
+  const tableBigint: [bigint[], bigint][] = [
+    [[0n], 0n],
+    [[1n], 1n],
+    [[1n, 2n, 3n, 4n, 5n], 120n],
+    [[1n, -2n, 3n, -4n, 5n], 120n]
+  ]
+
+  it.each(tableBigint)('product(%s) -> %s', (val, expected) => {
+    expect(product(val)).toBe(expected)
+  })
+})