Check if an Object is a Promise in JavaScript

README.md

Check if an Object is a Promise in JavaScript

https://debugpointer.com/check-if-an-object-is-a-promise/

Method 1

function isPromise(p) {
  return p && Object.prototype.toString.call(p) === "[object Promise]";
}

Method 2

function isPromise(value) {
  return Boolean(value && typeof value.then === "function");
}

Method 3

function isPromise(object) {
  if (Promise && Promise.resolve) {
    return Promise.resolve(object) == object;
  } else {
    throw "Promise not supported in your environment"; // Most modern browsers support Promises
  }
}

Method 4

function isPromise(obj) {
  return !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';
}