Example JS code on Promises using async/await with promise rejection

jsPromiseSample.js

async function capitalize(text, timeout) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      let firstChar = text.charAt(0);
      if (text.charAt(0).toUpperCase() === firstChar) {
        reject('First character is already capitalized');
      } else {
        resolve(text.charAt(0).toUpperCase() + text.slice(1));
      }
    }, timeout);
  });
}

async function createName(firstName, lastName) {
  let capitalizedFirstName = await capitalize(firstName, 200)
                                  .then(name => {return name;})
                                  .catch(e => {
                                    console.log(e);
                                    return firstName;
                                  });
  let capitalizedLastName = await capitalize(lastName, 300)
                                  .then(name => {return name;})
                                  .catch(e => {
                                    console.log(e);
                                    return lastName;
                                  });
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve(`${capitalizedFirstName} ${capitalizedLastName}`);
    }, 500);
  });
}

async function print(firstName, lastName) {
  let name = await createName(firstName, lastName);
  console.log(`Name: ${name}`);
}

print('john', 'doe');


async function print(firstName, lastName) {
  let name = await createName(firstName, lastName);
  console.log(`Name: ${name}`);
}

print('john', 'doe'); // Will not log any errors.
print('John', 'doe'); // Will cause an error to be logged. However it will not fail the program as the Promise rejection is handled.