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Resolve an object of promises

4 Jan, 2017

function runInParallel(input) {
    let keys = [];
    let promises = [];
    for (let key in input) {
        keys.push(key);
        promises.push(input[key]);
    }
    return Promise.all(promises).then((resolved) => {
        let output = {};
        for (let i=0; i<resolved.length; i++) {
            output[keys[i]] = resolved[i];
        }
        return output;
    });
}

const p1 = Promise.resolve(3);
const p2 = 1337;
const p3 = new Promise((resolve, reject) => {
  setTimeout(resolve, 100, "foo");
}); 
function p4() {
  return Promise.resolve(4);
}
runInParallel({p1, p2, p3, p4}).then(values => { 
  console.log(values); // { p1: 3, p2: 1337, p3: 'foo', p4: [Function: p4] }})
});