1-callbacks.js

function myAsyncFunction() {
  doSomethingAsync1(function(error, data1) {
    doSomethingAsync2(data1, function(error, data2) {
      console.log(data2);
    });
  });
}

2-promises.js

function myAsyncFunction() {
  doSomethingAsync1()
    .then(function(data1) {
      return doSomethingAsync2(data1);
    }, function() {
      // handle error
    })
    .then(function(data2) {
      console.log(data2);
    });
}

// or

function myAsyncFunction() {
  doSomethingAsync1()
    .then(doSomethingAsync2, handleError);
    .then(function(data2) {
      console.log(data2);
    });
}
 
function handleError() {
  // handle error
}

3-async-await.js

async function myAsyncFunction() {
  try {
    let data1 = await doSomethingAsync1();
    let data2 = await doSomethingAsync2(data1);
  } catch(error) {
    // handle error
  }
}