How to asynchronously process a dynamically sized array dependent on the fetch responses?-CodePudding

The following code works but is slow because I need to await each response instead of asynchronously processing the responses as they come in.

I imagine there is a way to do this with promises.all() but can't come up with a solution.

  let relatives = [ancestor];
  while (relatives.length > 0) {
    const nextRelative = relatives.pop();
    await fetchRelatives(nextRelative).then(relative => {
      relatives = relatives.concat(relative.ancestors);
    });
  }

We can assume the order is not important, as long as we process the entire tree.

CodePudding user response：

if The order of the answers is important to you. You have no choice but to use the async/await or generator functions.

CodePudding user response：

You can use promises:

Promise.all( relatives.map( task => fetchRelatives(task) ) ).then( results => {
    console.log('all responses:', results)
})

var results = await Promise.all( relatives.map( task => fetchRelatives(task) ) )

if relatives is added dynamically, then this should work:

var do_task = async( relative ) => {
    if (relative) 
        relatives.push(... relative.ancestors)
    
    if (relatives.length)
        return fetchRelatives( relatives.pop() ).then( person => do_task( person ) )
}

/// 4 workers:
Promise.all( Array(4).fill().map( do_task ) ).then(() => console.log('all done'))