question

interviewQuestion

  Fetcher interface:
  fetchAnimals(prefix: string, callback: function): void
  fetchArticles(prefix: string, callback: function): void
  fetchFruits(prefix: string, callback: function): void
  Note: there are many more fetchers
 
  Callback interface:
  callback(results: string[]): void
*/
fetchAnimals('g', (results) => console.log(results));
// Might eventually print: ['gorilla', 'giraffe']
fetchFruits('g', (results) => {
   // do something with results
   alert(results);
});
// Might eventually print: ['grape', 'guava']
/* … and more! */
const fetchAll = combineFetchers([fetchAnimals, fetchFruits, /* … etc. */]);
const fetchMedia = combineFetchers([fetchVideos, fetchMovies, fetchBooks]);
fetchAll('g', (results) => console.log(results));
// Might eventually print: ['giraffe', 'gorilla', 'grape', 'guava', ...]
fetchAll('gi', (results) => console.log(results));
// Might eventually prints: ['giraffe']
// TODO: implement combineFetchers

+++++++++++++++++++++++++++++++++++++++++++++++++++++++
Input: array of functions 
output: an array of result values of each function

function combineFetchers(fetchers) {
    /*
    return a function: input: prefix, function
    */
    return function (prefix, func) {
        let arr = []
        for(let i = 0; i < fetchers.length; i++) {
            fetchers[i](prefix, (results) => {
                // handle results
                for (const result of results) {
                    arr.push(result);
                }
                if (i == fetchers.length-1) {
                    func(arr);
                }
            });
        }
    }
}

Notes: Implement a fetcher interface, as shown above, but the callback functions are the fetchAll, fetchMedia