how to call function asynchronously in javascript code example

Example 1: async await

async function f() {

  try {
    let response = await fetch('/no-user-here');
    let user = await response.json();
  } catch(err) {
    // catches errors both in fetch and response.json
    alert(err);
  }
}

f();

Example 2: await async

function afterPrintSave() {
    Xrm.Page.data.save().then(
        function () {
            resolve();
        },
        function (err) {
            resolve(alert(err.message));
        }
    );
}