feat: add Array.prototype.chain_

tdreyno · Jan 8, 2021 · 7a1a7ae · 7a1a7ae
1 parent 3221e37
commit 7a1a7ae
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diff --git a/src/__tests__/util.spec.ts b/src/__tests__/util.spec.ts
@@ -50,3 +50,12 @@ describe("mapToIndexedObject", () => {
     })
   })
 })
+
+describe("Array.prototype.chain_", () => {
+  test("should allow Array chaining", () => {
+    const sum = (arr: number[]) => arr.reduce((a, b) => a + b, 0)
+    const result = [1, 2, 3].chain_(sum)
+
+    expect(result).toEqual(6)
+  })
+})
diff --git a/src/util.ts b/src/util.ts
@@ -36,3 +36,16 @@ export const pairsToIndexedObject = <V, R extends { [key: string]: V }>(
   sum: R,
   [key, value]: [string, V],
 ): R => (((sum as { [key: string]: V })[key] = value), sum)
+
+declare global {
+  interface Array<T> {
+    chain_<U>(fn: (arr: Array<T>) => U): U
+  }
+}
+
+Array.prototype.chain_ = function <T, U>(
+  this: Array<T>,
+  fn: (arr: Array<T>) => U,
+): U {
+  return fn(this)
+}