Promise after delay

Question

I have this problem that I cannot seem to know how to tackle? Write a function, promised, that takes in a value. This function will return a promise that will resolve after 2 seconds. The following code should not be edited and should use the promise object.

 function promised (val) {
     
    }
    
    // UNCOMMENT THESE TO TEST YOUR WORK!
     const createPromise = promised('wait for it...');
     createPromise.then((val) => console.log(val)); 
    // will log "wait for it..." to the console after 2 seconds

Answer 1

const sleep = async (time) => {
    return new Promise(resolve => setTimeout(resolve, time * 1000))
}



const sayHello = async () => {
    await sleep(2)
    console.log('Hello there')
}


sayHello()

Here is the explanation:

Use The setTimeout() which is a builtin method that calls a function or evaluates an expression after a specified number of milliseconds. setTimeout() takes 2 parameters the first one is a call back function and the second one is the number of the milliseconds. 1 second = 1000ms so 2 seconds = 2000ms and so on

function promised (val) {
    // Create a new promise and resolve val after 2 seconds
    return new Promise(resolve => setTimeout(() => resolve(val), 2000)) //2000ms => 2 seconds
}



const createPromise = promised('wait for it...') // Pass in your message to promised function

createPromise
    .then(val => console.log(val))
    // Catch errors if any you don't need it here since we are always resolving the promise i just included it here so you know it's exist 
    .catch(err => console.log(err)) 

you should always use .catch unless you are 100% sure that the promise will always resolve

example:

function greeting(name) {

    return new Promise((resolve, reject) => setTimeout(() => {
        
        try {
            
            if (name.length <= 2) {
                throw new Error('Name must be more than two characters')
            }

        } catch (msg) {
            reject(msg)
        } 

        resolve(`Hello ${name}`)
        
        
    }, 2000))
}


greeting('ab')
    .then(res => console.log(res))
    .catch(err => console.log(err)) // Error: Name must be more than two characters

greeting('John')
    .then(res => console.log(res)) // Hello John
    .catch(err => console.log(err))

Using async, await:

const greetSomeone = async (name) => {

    try {

        // Note that you can't use await outside an async function
        const msg = await greeting(name) 
        console.log(msg)

    } catch (err) {
        console.log(err)
    }
}



greetSomeone('ac') // Error: Name must be more than two characters

greetSomeone('Michael') // Hello Michael

Learn more about Promises https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise