Web/JavaScript/Reference/Global objects/Promise/resolve

The Promise.resolve() method returns a Promise object that is resolved with a given value. If the value is a promise, that promise is returned; if the value is a thenable (i.e. has a "then" method), the returned promise will "follow" that thenable, adopting its eventual state; otherwise the returned promise will be fulfilled with the value. This function flattens nested layers of promise-like objects (e.g. a promise that resolves to a promise that resolves to something) into a single layer.

Syntax

Promise.resolve(value);

Parameters

value: Argument to be resolved by this Promise. Can also be a Promise or a thenable to resolve.

Return value

A Promise that is resolved with the given value, or the promise passed as value, if the value was a promise object.

Description

The static Promise.resolve function returns a Promise that is resolved.

Examples

Using the static Promise.resolve method

Promise.resolve('Success').then(function(value) {
  console.log(value); // "Success"
}, function(value) {
  // not called
});

Resolving an array

var p = Promise.resolve([1,2,3]);
p.then(function(v) {
  console.log(v[0]); // 1
});

Resolving another Promise

var original = Promise.resolve(33);
var cast = Promise.resolve(original);
cast.then(function(value) {
  console.log('value: ' + value);
});
console.log('original === cast ? ' + (original === cast));

// logs, in order:
// original === cast ? true
// value: 33

The inverted order of the logs is due to the fact that the then handlers are called asynchronously. See how then works here.

Resolving thenables and throwing Errors

// Resolving a thenable object
var p1 = Promise.resolve({ 
  then: function(onFulfill, onReject) { onFulfill('fulfilled!'); }
});
console.log(p1 instanceof Promise) // true, object casted to a Promise

p1.then(function(v) {
    console.log(v); // "fulfilled!"
  }, function(e) {
    // not called
});

// Thenable throws before callback
// Promise rejects
var thenable = { then: function(resolve) {
  throw new TypeError('Throwing');
  resolve('Resolving');
}};

var p2 = Promise.resolve(thenable);
p2.then(function(v) {
  // not called
}, function(e) {
  console.error(e); // TypeError: Throwing
});

// Thenable throws after callback
// Promise resolves
var thenable = { then: function(resolve) {
  resolve('Resolving');
  throw new TypeError('Throwing');
}};

var p3 = Promise.resolve(thenable);
p3.then(function(v) {
  console.log(v); // "Resolving"
}, function(e) {
  // not called
});

Specifications

Specification

ECMAScript (ECMA-262)The definition of 'Promise.resolve' in that specification.

Browser compatibility

To contribute to this compatibility data, please write a pull request against this repository: https://github.com/mdn/browser-compat-data.

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`resolve()`	Chrome Full support 32	Edge Full support 12	Firefox Full support 29	IE No support No	Opera Full support 19	Safari Full support 8	WebView Android Full support 4.4.3	Chrome Android Full support 32	Firefox Android Full support 29	Opera Android Full support 19	Safari iOS Full support 8	Samsung Internet Android Full support 2.0	nodejs Full support 0.12

Legend

Full support: Full support
No support: No support