Advanced Node.js Development

Returning a new promise

Now, in the getGrades variable, we're going to get the schoolId that we're using to look things up with. Then we're going to go ahead and return a new promise; this is all part of the contrived example, resolve and reject are our two arguments:

const getGrades = (schoolId) => {  return new Promise((resolve, reject) => {   });};

Then, right here, we're going to go ahead and resolve the filtered grades array, that is grades.filter. We're going to filter this one by passing an arrow function. It'll get called with the individual grade, not user, and then we'll go ahead and implicitly return something. If we return true, it'll be considered a match and that grade will be resolved. If we return false, that grade will be removed ...