feat: isPromise (#3)

LuciNyan · Mar 3, 2023 · 6d2a198 · 6d2a198
1 parent 89149d8
commit 6d2a198
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diff --git a/src/base.test.ts b/src/base.test.ts
@@ -8,6 +8,7 @@ import {
   isNull,
   isNumber,
   isObject,
+  isPromise,
   isRegExp,
   isString,
   isSymbol,
@@ -219,3 +220,18 @@ describe('isWindow', () => {
     expect(isWindow({})).toBe(false)
   })
 })
+
+describe('isPromise', () => {
+  it('should return true if value is a Promise', () => {
+    expect(isPromise(new Promise(() => {}))).toBe(true)
+    expect(isPromise(Promise.resolve())).toBe(true)
+  })
+  it('should return false if value is not a Promise', () => {
+    expect(isWindow(undefined)).toBe(false)
+    expect(isWindow(null)).toBe(false)
+    expect(isWindow(123)).toBe(false)
+    expect(isWindow('string')).toBe(false)
+    expect(isWindow(true)).toBe(false)
+    expect(isWindow({})).toBe(false)
+  })
+})
diff --git a/src/base.ts b/src/base.ts
@@ -48,6 +48,10 @@ export function isWindow(x: unknown): x is Window {
   return toString(x) === '[object Window]'
 }
 
+export function isPromise(x: unknown): x is Promise<unknown> {
+  return toString(x) === '[object Promise]'
+}
+
 export function isIterator(obj: unknown): obj is Iterator<unknown> {
   return isObject(obj) && obj !== null && typeof (obj as any)[Symbol.iterator] === 'function'
 }