when is async javascript introduced in javascript code example

Example 1: async await javascript

function hello() {
  return new Promise((resolve,reject) => {
    setTimeout(() => {
      resolve('I am adam.');
    }, 2000);
  });
}
async function async_msg() {
  try {
    let msg = await hello();
    console.log(msg);
  }
  catch(e) {
    console.log('Error!', e);
  }
}
async_msg(); //output - I am adam.

Example 2: async await javascript

myFunction().then(

  function(value) { /* code if successful */ },

  function(error) { /* code if some error */ }

);