How it works: Promises - Async/Await - [JavaScript]

promises_async_await.js

/**
 * Create a promise and assign it to a variable
 */
let promise = new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve('Success!')
    }, 2000)
});

/**
 * Assign the result of the promise to a variable
 * In this case we are assigning the result of the promise to the promise_result variable
 */
let promise_result = promise.then((successMessage) => {
    console.log(successMessage)
})

console.log(promise_result)
/**
 * output:
 * Promise { <pending> } // First, the console.log(promise_result) is executed which returns the promise in pending status.
 * Success! // Then the console.log(successMessage) is executed which returns the promise message
 */

/**
 * To avoid running the console.log(promise_result) before the console.log(successMessage)
 * An asynchronous function will be created and executed when the promise is resolved.
 */
let second_promise = new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve('Success!')
    }, 2000)
})

async function asyncFunction() {
    let result = await second_promise; // await: Indicates to wait until the pledge is resolved (*)
    console.log(result); // "done!"
}

asyncFunction();
/**
 * output:
 * Success! // Wait for the promise to resolve and then run the console.log [after 2 seconds].
 */