js_morning_2.js

/*******************
 warm up
 *******************/

function* generateAlphaBet() {
  let i = "a".charCodeAt(0);
  let end = "z".charCodeAt(0) + 1;

  while(i < end) {
    yield String.fromCharCode(i);
    i++;
  }
}

// destructure like a Boss
const {0: first, length, [length-1]: last} = [...generateAlphaBet()];

console.log(first); // -> a
console.log(last);  // -> b

/*******************
 transform streams with generators
 *******************/

function* transform(iterable, tFn) {
  for(const v of iterable) {
    yield tFn(v)
  }
}

function* map(iterable, mapFn) {
  yield* transform(iterable, mapFn)
}

const users = [
  { fName: 'nir', lName: 'kaufman'},
  { fName: 'udi', lName: 'mazor'},
  { fName: 'Yaniv', lName: 'falik'},
]

// MOD === Map On Damned!
const MOD = map(users, user => ({ name: `${user.fName} ${user.lName}` }))

// Map one after each other
console.log(MOD.next().value);
console.log(MOD.next().value);
console.log(MOD.next().value);

// Push new users
users.push({ fName: 'nitsan', lName: 'zohar' });

// continue
console.log(MOD.next().value);