Looping with Promises in JS

Question

I am trying to run queries inside a for loop in nodejs and each iteration of the for loop runs one query. The queries are done with a "get()" method that returns a Promise. In my function (that contains this for loop), I am returning the promise returned by the get() method like so:

for(var i=0; i < productIds.length; i++) { return queryObject.get(productIds[i]).then(//handle result) }

but this returns after the first iteration and doesn't continue for the rest of the iterations. How do I solve this issue?

For context, I am using Parse's Cloud Functions.

Answer 1

You have to build up a promise chain like so:

let chain = Promise.resolve();

for (i=0; i<1000; i++) {
   chain = chain.then(()=>queryObject.get(objectId))
}

chain.then(()=>{ /* do something once all queries have returned a result */})