프로마이스

doSomething() 

.then( result => doSomethingElse(result) ) 

.then(newResult => doThirdThing(newResult)) 

.then(finalResult => { console.log(`Got the final result: ${finalResult}`); }) 

.catch(failureCallback);

var promise1 = new Promise(function(resolve, reject) {

  setTimeout(function() {

    resolve('foo');

  }, 300);

});

promise1.then(function(value) {

  console.log(value);

  // expected output: "foo"

});

console.log(promise1);

// expected output: [object Promise]