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Promise

Basic​

Creation of Promise​

const promise = new Promise((res, rej) => {
  // do some stuffs
  if() {
    res("holy cow"); // param of res will be returned
  } else {
    rej({message: 'something', code:'404'}); // param of rej will be returned + exception will be throwed
  }
});

Resolve​

There are 2 ways of waiting on a promise.

awaiting on Promise​

Make sure you call it from an asyn function

try {
  const val = await promise;
  console.log(val); // "holy cow"
} catch (exc) {
  console.log(exc.message); // "something"
}

awaiting on Promise​

Make sure you call it from an asyn function

promise
  .then((data) => {
    console.log(data); // "holy cow"
  })
  .catch((data) => {
    console.log(data.message); // "something"
  });