sindresorhus / p-is-promise

Check if something is a promise

p-is-promise

Check if something is a promise

Why not is-promise? That module checks for a thenable, not an ES2015 promise. This one is stricter.

You most likely don't need this. Just pass your value to Promise.resolve() and let it handle it.

Can be useful if you need to create a fast path for a synchronous operation.

Install

$ npm install p-is-promise

Usage

import isPromise from 'p-is-promise';
import Bluebird from 'bluebird';

isPromise(Promise.resolve('🦄'));
//=> true

isPromise(Bluebird.resolve('🦄'));
//=> true

isPromise('🦄');
//=> false

Related

• is - Type check values
• More…

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p-is-promise's Issues

Genuine question

Why?

Would it be easier for all, reduce bundle sizes and over all development complexity if instead of being a whole NPM package, it was just a README that said

To check if a value is a promise, simply do the following:
    value instanceof Promise

Even works on Node 11 (probably)!

Doesn't handle promises that are functions

“thenable” is an object or function that defines a then method.

-- https://promisesaplus.com/

So typeof input === 'object' is incomplete/incorrect:

p-is-promise/index.js

Line 7 in cda35a5

typeof input === 'object' &&