Promise & async await & TypeScript

[xgqfrms]

Promise & async await & TypeScript

type P = Promise<number>

async function addTwoPromises(promise1: P, promise2: P): P {
   const [a, b] = await Promise.all([promise1, promise2]);
    return a + b;
    // return Promise.resolve(a + b);
};
// async function addTwoPromises(promise1: P, promise2: P): P {
//     const a = await promise1;
//     const b = await promise2;
//     // const a = await promise1.then(v => v);
//     // const b = await promise2.then(v => v);
//     return Promise.resolve(a + b)
// };

/**
 * addTwoPromises(Promise.resolve(2), Promise.resolve(2))
 *   .then(console.log); // 4
 * 
 */

https://leetcode.com/problems/add-two-promises/?envType=study-plan-v2&envId=30-days-of-javascript

// promise function ⚠️
function resolveAfter2Seconds() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve('resolved');
    }, 2000);
  });
}

async function asyncCall() {
  console.log('calling');
  const result = await resolveAfter2Seconds();
  console.log(result);
  // Expected output: "resolved"
}

asyncCall();

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function

async function f() {
  // new Promise ✅
  let promise = new Promise((resolve, reject) => {
    setTimeout(() => resolve("done!"), 1000)
  });

  let result = await promise; // wait until the promise resolves (*)

  console.log(result); // "done!"
} 

f();

https://javascript.info/async-await