Add is.asyncIterable

source/index.ts

@@ -136,6 +136,7 @@ namespace is { // tslint:disable-line:no-namespace
 	export const nullOrUndefined = (value: any): value is null | undefined => null_(value) || undefined(value);
 	export const object = (value: any): value is object => !nullOrUndefined(value) && (function_(value) || isObject(value));
 	export const iterable = (value: any): value is IterableIterator<any> => !nullOrUndefined(value) && function_(value[Symbol.iterator]);
+	export const asyncIterable = (value: any): value is AsyncIterableIterator<any> => !nullOrUndefined(Symbol.asyncIterator) && typeof value[Symbol.asyncIterator] === 'function';
 	export const generator = (value: any): value is Generator => iterable(value) && function_(value.next) && function_(value.throw);
 
 	export const nativePromise = (value: any): value is Promise<any> =>

source/tests/test.ts

@@ -10,6 +10,7 @@ import ZenObservable from 'zen-observable';
 import m from '..';
 
 const isNode8orHigher = Number(process.versions.node.split('.')[0]) >= 8;
+const isNode10orHigher = Number(process.versions.node.split('.')[0]) >= 10;
 
 class PromiseSubclassFixture<T> extends Promise<T> {}
 class ErrorSubclassFixture extends Error {}
@@ -337,6 +338,14 @@ const types = new Map<string, Test>([
 			Infinity,
 			-Infinity
 		]
+	}],
+	['asyncIterable', {
+		is: m.asyncIterable,
+		fixtures: [
+			Object.create({
+				[Symbol.asyncIterator]: () => {} // tslint:disable-line:no-empty
+			})
+		]
 	}]
 ]);
 
@@ -454,6 +463,14 @@ if (isNode8orHigher) {
 	});*/
 }
 
+if (isNode10orHigher) {
+	test('is.asyncIterable', t => {
+		t.true(m.asyncIterable(Object.create({
+			[Symbol.asyncIterator]: () => {} // tslint:disable-line:no-empty
+		})));
+	});
+}
+
 test('is.generator', t => {
 	testType(t, 'generator');
 });

tsconfig.json

@@ -6,7 +6,8 @@
 			"dom",
 			"es2015",
 			"es2016",
-			"es2017.sharedmemory"
+			"es2017.sharedmemory",
+			"esnext.asynciterable"
 		],
 		"module": "commonjs",
 		"moduleResolution": "node",