From 4ff691d87f38c2fac80ab884ae9edbb5a506df02 Mon Sep 17 00:00:00 2001
From: Vladimir Ivakin <vla.ivakin@gmail.com>
Date: Tue, 30 Jul 2024 20:50:52 +0200
Subject: [PATCH] Add withResolvers

---
 docs/async/withResolvers.mdx      | 16 ++++++++++++++++
 src/async/withResolvers.ts        | 30 ++++++++++++++++++++++++++++++
 src/mod.ts                        |  1 +
 tests/async/withResolvers.test.ts | 19 +++++++++++++++++++
 4 files changed, 66 insertions(+)
 create mode 100644 docs/async/withResolvers.mdx
 create mode 100644 src/async/withResolvers.ts
 create mode 100644 tests/async/withResolvers.test.ts

diff --git a/docs/async/withResolvers.mdx b/docs/async/withResolvers.mdx
new file mode 100644
index 00000000..e5dcd099
--- /dev/null
+++ b/docs/async/withResolvers.mdx
@@ -0,0 +1,16 @@
+---
+title: withResolvers
+description: Ponyfill for Promise.withResolvers()
+---
+
+### Usage
+
+Creates a new promise and returns the resolve and reject functions along with the promise itself.
+
+The ponyfill for https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers
+
+```ts
+const { resolve, reject, promise } = withResolvers()
+
+resolve(42)
+```
diff --git a/src/async/withResolvers.ts b/src/async/withResolvers.ts
new file mode 100644
index 00000000..a5a24f33
--- /dev/null
+++ b/src/async/withResolvers.ts
@@ -0,0 +1,30 @@
+interface PromiseWithResolvers<T> {
+  promise: Promise<T>
+  resolve: (value: T | PromiseLike<T>) => void
+  reject: (reason?: any) => void
+}
+
+/**
+ * Creates a new promise and returns the resolve and reject functions along with the promise itself.
+ *
+ * The ponyfill for https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers
+ *
+ * @see https://radashi-org.github.io/reference/async/withResolvers
+ * @example
+ * ```ts
+ * const {resolve, reject, promise} = withResolvers()
+ *
+ * resolve(42)
+ * ```
+ */
+export function withResolvers<T>(): PromiseWithResolvers<T> {
+  let resolve: any
+  let reject: any
+
+  const promise = new Promise<T>((res, rej) => {
+    resolve = res
+    reject = rej
+  })
+
+  return { resolve, reject, promise }
+}
diff --git a/src/mod.ts b/src/mod.ts
index ae47f9bf..0720a12c 100644
--- a/src/mod.ts
+++ b/src/mod.ts
@@ -39,6 +39,7 @@ export * from './async/reduce.ts'
 export * from './async/retry.ts'
 export * from './async/sleep.ts'
 export * from './async/tryit.ts'
+export * from './async/withResolvers.ts'
 
 export * from './curry/callable.ts'
 export * from './curry/chain.ts'
diff --git a/tests/async/withResolvers.test.ts b/tests/async/withResolvers.test.ts
new file mode 100644
index 00000000..c5adbaed
--- /dev/null
+++ b/tests/async/withResolvers.test.ts
@@ -0,0 +1,19 @@
+import * as _ from 'radashi'
+
+describe('withResolvers', () => {
+  test('resolves promise', async () => {
+    const { resolve, promise } = _.withResolvers<number>()
+
+    resolve(42)
+
+    expect(await promise).toBe(42)
+  })
+
+  test('rejects promise', async () => {
+    const { reject, promise } = _.withResolvers<number>()
+
+    reject('Weird error')
+
+    await expect(promise).rejects.toThrowError('Weird error')
+  })
+})