Promise () javacsript code example

Example 1: javascript promise

var promise = new Promise(function(resolve, reject) {
  // do some long running async thing…
  
  if (/* everything turned out fine */) {
    resolve("Stuff worked!");
  }
  else {
    reject(Error("It broke"));
  }
});

//usage
promise.then(
  function(result) { /* handle a successful result */ },
  function(error) { /* handle an error */ }
);

Example 2: Promise

let doSecond = () => {
  console.log('Do second.')
}

let doFirst = new Promise((resolve, reject) => {
  setTimeout(() => {
    console.log('Do first.')

    resolve()
  }, 500)
})

doFirst.then(doSecond)