Promise.resolve

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

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

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

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

// 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
});