Promise all then resolve

Question

Using Node 4 x  When you have a Promise all promises  then   what is the proper way to resolve the data and pass it to the next  then     I want to do something like this   Promise all promises  then function data        Do something with the data here    then function data        Do more stuff here       But I m not sure how to get the data to the 2nd  then    I can t use resolve      in the first  then    I figured out I can do this   return Promise all promises  then function data        Do something with the data here   return data     then function data        Do more stuff here       But that doesn t seem like the proper way to do it    What is the right approach to this

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Today NodeJS supports new async await syntax  This is an easy syntax and makes the life much easier  async function process promises       must be an async function     let x   await Promise all promises       now x will be an array     x   x map  tmp   gt  tmp   10                   proccessing the data     const promises        new Promise resolve   gt  setTimeout resolve  0  1       new Promise resolve   gt  setTimeout resolve  0  2       process promises    Learn more    https   developer mozilla org en-US docs Web JavaScript Reference Statements async function

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Your return data approach is correct  that s an example of promise chaining  If you return a promise from your  then   callback  JavaScript will resolve that promise and pass the data to the next then   callback   Just be careful and make sure you handle errors with  catch    Promise all   rejects as soon as one of the promises in the array rejects

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But that doesn t seem like the proper way to do it     That is indeed the proper way to do it  or at least a proper way to do it   This is a key aspect of promises  they re a pipeline  and the data can be massaged by the various handlers in the pipeline   Example    x000D   x000D  const promises     x000D    new Promise resolve   gt  setTimeout resolve  0  1    x000D    new Promise resolve   gt  setTimeout resolve  0  2   x000D     x000D  Promise all promises  x000D     then data   gt    x000D      console log  First handler   data   x000D      return data map entry   gt  entry   10   x000D       x000D     then data   gt    x000D      console log  Second handler   data   x000D        x000D   x000D   x000D     catch handler omitted for brevity  In production code  always either propagate the promise  or handle rejection    The output we see from that is    First handler  1 2  Second handler  10 20       because the first handler gets the resolution of the two promises  1 and 2  as an array  and then creates a new array with each of those multiplied by 10 and returns it  The second handler gets what the first handler returned   If the additional work you re doing is synchronous  you can also put it in the first handler   Example    x000D   x000D  const promises     x000D    new Promise resolve   gt  setTimeout resolve  0  1    x000D    new Promise resolve   gt  setTimeout resolve  0  2   x000D     x000D  Promise all promises  x000D     then data   gt    x000D      console log  Initial data   data   x000D      data   data map entry   gt  entry   10   x000D      console log  Updated data   data   x000D      return data  x000D        x000D   x000D   x000D       but if it s asynchronous you won t want to do that as it ends up getting nested  and the nesting can quickly get out of hand

[javascript] Promise.all().then() resolve?

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