a generic function that sequencialy run a function on a promiss array

waitForEach.js

const waitForEach = (processFunc , [head, ...tail]) =>
    !head
        ? Promise.resolve()
        : processFunc(head).then(waitForEach(processFunc , tail));





// example of usage
function proceessAllUser() {
    const sql = 'SELECT ID FROME users';
    return db.query(sql , [])
        .then( users => waitForEach(user => processUser(user.id) , users))
}