How to access the Value of a Promise in JavaScript

In this article, we will see how to access the value of Promise in JavaScript. The Promise is a feature of ES6 introduced in 2015. The concept of Promises is generally used when we want to work asynchronously.

The value of a Promise can be accessed in JavaScript using the following methods.

Syntax:

let promise = new Promise((resolve, reject)=>{//enter the code})

Approach: Using .then( ) Method

• In this code example, we have created a variable createPromise which is a promise having two callbacks provided by javascript.
• resolve: when the promise resolves successfully.
• reject: when the promise is rejected for any reason.
• Then creating setTimeout has a callback function that will run after two seconds.
• By using the .then( ) method access the value of the Promise.

Example: The code example shows how to access the value of a Promise in JavaScript using the .then method.

console.log("wait for 2 seconds to get promise resolved")
const createPromise = new Promise(
    (resolve, reject) => {
        setTimeout(function () {
            resolve(
                "the promise is resolved after 2 seconds");
        }, 2000)
    });

createPromise.then((promisedata) => {
    console.log("Promise is resolved successfully", promisedata)
})

Output:

Approach 2: Using the Async/Await Method

• An async function looks like simple JavaScript function but it has the feature of working with await expressions.
• promisefun is a async function and in the body of that function there is an await expression that waits promise to resolve once it resolved the user access the value of the promise.
• We have used the setTimeout and in callback function we have resolve the promise with the string after two seconds.
• Then, call the async function as promiseFun().

Example: The example show access the value of a Promise in JavaScript using async/await method.

console.log("wait for 2 seconds to get promise resolved")

async function promiseFun() {
const createPromise = new Promise(
    (res, rej) => {
        setTimeout(function () {
            res(
                "the promise resolved");
        }, 2000)
    });
    const waitPromise = await createPromise 
    console.log(waitPromise)
}
promiseFun()

Output: