Get first truthy promise result

promise-first-truthy.ts

function firstTruthy<T>(promises: Array<Promise<any>>): Promise<T|null> {
    return new Promise((resolve, reject) => {
        // If any promise returns truthy value, immediately resolve with it
        promises.forEach(async promise => {
            const result = await promise;
            if (!!result) resolve(result);
        });

        // If any promise rejects, immediately throw the error
        Promise.race(promises).catch(reject);

        // If neither of the above fires, resolve with a null
        // Check truthiness just in case callbacks fire out-of-band
        Promise.all(promises).then(results => {
            const truthyResult = results.find(result => !!result);
            truthyResult ? resolve(truthyResult) : resolve(null);
        });
    });
}