有没有更简单的方法来暂停执行然后在异步 function 上进行回调？

Question

I have a nodejs application where I download a file which is then immediately used and the rest of the program depends on that file being used, the only problem is that the only function I have to download the file through Google Cloud is asynchronous which means in order to stop the program from immediately crashing when it realizes the file hasn't been fully downloaded is to stick a callback on my asyncronous function for downloading.

This would normally be fine, but unfortunately the rest of the program is around 400 LINES LONG which means a 400 LINE LONG CALLBACK FUNCTION. Which is understandably ugly.

If anyone can tell me of a simpler method for pausing execution than this callback function, I would appreciate it.

Feel free to let me know if this is a duplicate question and this exact one has been answered elsewhere. I scoured for this question myself, but couldn't find it.

 async function downloader(callback){ await download(file); //insert download function here callback(); } downloader(function(){ var usefulthing = JSON.parse(file); //Insert 400 lines of code here });

Answer 1

You can separate your 400 lines of code into a file and export a function, let say named handleFile . Then in your callback function just call:

downloader(function(){
  var usefulthing = JSON.parse(file);
  handleFile(file)
});

Answer 2

const Downloader=async()=>{

   const file = await download(file)
    // this now returns the file as a promise 
   return file 
}
function MainStuff async(){
   const file =await Downloader()
  // the 400 lines of code now will wait this file to finish downloading
}