30-seconds-of-code
Version:
A collection of useful JavaScript snippets.
23 lines (18 loc) • 620 B
Markdown
Returns `true` if an object looks like a [`Promise`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise), `false` otherwise.
Check if the object is not `null`, its `typeof` matches either `object` or `function` and if it has a `.then` property, which is also a `function`.
```js
const isPromiseLike = obj =>
obj !== null &&
(typeof obj === 'object' || typeof obj === 'function') &&
typeof obj.then === 'function';
```
```js
isPromiseLike({
then: function() {
return '';
}
}); // true
isPromiseLike(null); // false
isPromiseLike({}); // false
```