How to create a loop of promises

If you want to loop and serialise the promises, not executing any other get calls once one fails, then try this loop:

async function getAllResults() {  // returns a promise for 250 results
    let totalResults = [];
    try {
        for (let i = 0; i < 5; i++) {
            totalResults.push(...await getResults.get());
        }
    } catch(e) {};
    return totalResults;
}

This uses the EcmaScript2017 async and await syntax. When not available, chain the promises with then:

function getAllResults() {
    let totalResults = [];
    let prom = Promise.resolve([]);
    for (let i = 0; i < 5; i++) {
        prom = prom.then(results => {
            totalResults = totalResults.concat(results);
            return getResults.get();
        });
    }
    return prom.then(results => totalResults.concat(results));
}

Note that you should avoid the promise construction anti-pattern. It is not necessary to use new Promise here.

Also consider adding a .catch() call on the promise returned by the above function, to deal with error conditions.

Finally, be aware that concat does not modify the array you call it on. It returns the concatenated array, so you need to assign that return value. In your code you don't assign the return value, so the call has no effect.

See also JavaScript ES6 promise for loop.

Probably you just need Promise.all method. For every request you should create a promise and put it in an array, then you wrap everything in all method and you're done.

Example (assuming that getResults.get returns a promise):

let promiseChain = [];
for(let i = 0; i <5; i++){
    promiseChain.push(getResults.get());
}

Promise.all(promiseChain)
    .then(callback)

You can read more about this method here: Promise.all at MDN

EDIT You can access data returned by the promises this way:

function callback(data){
    doSomething(data[0]) //data from the first promise in the chain
    ...
    doEventuallySomethingElse(data[4]) //data from the last promise
}