Wait for two async functions to finish then continue in Node.js

You can use Promise.all here, to wait for the two promises and then work with their data:

let promises = [];
let x = 'abcd';
promises.push(foo(x))

x = 'efgh';
promises.push(foo(x))

Promise.all(promises).then(([a, b]) => {
  console.log(a, b); // for example
});


function foo(d) {
  return Promise.resolve({somePaddingData:"", d});
}

As foo returns a Promise you should mark your function as asyncronus with async keyword and wait for the foo function to respond with the await keyword.

 async function someFunction(){   
  let x = 'abcd';
  let a = await  foo(x);

  x = 'efgh';
  let b = await foo(x);
  console.log(a + b)
}