promiseAll.js

class MyPromise {
    static all(promises) {
    	let results = []; // to be resolved array of values
        let completedPromises = 0;
      	// return a promise
        return new Promise((resolve, reject) => {
          promises.forEach((promise, index) => {
            promise.then((value) => {
              results[index] = value;
              completedPromises += 1;
              if(completedPromises === promises.length) {
                // to break the loop
                resolve(results);
              }
            }).catch(function (error) {
              reject(error);
            });
          });
        });
    }
}