Finally Method on Promises

Usually, if a promise is resolved, we take action in then block. If it errors out, we use the catch block. What if there is an action you would like to take regardless of the outcome? Maybe it is cleanup or displaying a message to the user that the promise has finished. The finally() method is used to invoke a callback function once a promise is settled no matter what the outcome. finally return a Promise.

Keep in mind that the finally method cannot receive any argument as there is no way to know if the promise was resolved or rejected.

Syntax

promise
    .then(response => {
        // handle success
    })
    .catch(error => {
        // handle error
    })
    .finally(() => {
        // take any action
    })

Example

const apiCall = (name) => {
    return new Promise((resolve, reject) => {
        if(name === "Parwinder"){
            resolve("Parwinder works here.")
        } else {
            reject(`${name} is not an employee.`)
        }
    });
}

apiCall("Parwinder")
    .then((response) => {
        console.log(response); // Parwinder works here.
    })
    .finally(() => {
        console.log("Is there anything else I can help you with?"); // Is there anything else I can help you with?
    });

apiCall("Lauren")
    .catch((err) => {
        console.log(err); // Lauren is not an employee.
    })
    .finally(() => {
        console.log("Maybe you would like to try a different employee name?"); // Maybe you would like to try a different employee name?
    })

In both the scenarios (resolve and reject), we can display a follow-up message using finally.