TypeError: 'x' is not iterable

var obj = { France: "Paris", England: "London" };
for (let p of obj) {
  // TypeError: obj is not iterable
  // 
}

var obj = { France: "Paris", England: "London" };
//    iterate:
for (let country of Object.keys(obj)) {
  var capital = obj[country];
  console.log(country, capital);
}

for (const [country, capital] of Object.entries(obj))
  console.log(country, capital);

var map = new Map();
map.set("France", "Paris");
map.set("England", "London");
//    iterate
for (let country of map.keys()) {
  let capital = map[country];
  console.log(country, capital);
}

for (let capital of map.values()) console.log(capital);

for (const [country, capital] of map.entries()) console.log(country, capital);

function* generate(a, b) {
  yield a;
  yield b;
}

for (let x of generate)
  // TypeError: generate is not iterable
  console.log(x);

function* generate(a, b) {
  yield a;
  yield b;
}

for (let x of generate(1, 2)) console.log(x);