The Promise.resolve(value) method returns a Promise object that is resolved with the given value. If the value is a thenable (i.e. has a "then" method), the returned promise will "follow" that thenable, adopting its eventual state; if the value was a promise, that object becomes the result of the call to Promise.resolve; otherwise the returned promise will be fulfilled with the value.

Syntax

Promise.resolve(value);
Promise.resolve(promise);
Promise.resolve(thenable); 

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.log(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 Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Promise.resolve' in that specification.
Standard Initial definition in an ECMA standard.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Promise.resolve' in that specification.
Living Standard  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic Support32.0 (Yes)29.0 No197.1
FeatureAndroidChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic Support4.4.432.0 (Yes)29 No (Yes)8.0

See also

Document Tags and Contributors

 Contributors to this page: Jiang-Xuan, fscholz, amm0nium, nmve, kdex, eduardoboucas, Sheepy, realityking
 Last updated by: Jiang-Xuan,