對象，數組，Set，Map的遍歷方法

var a = ['A', 'B', 'C'];

for(var i of a.keys()) {
  console.log(i)
}

for (var i of a) {
  console.log(i)
}

a.forEach(function (element, index, array) {
  console.log(element + ', index = ' + index);
});

var s = new Set(['A', 'B', 'C']);
s.forEach(function (element, sameElement, set) {
  console.log(`${element}${sameElement}`);
});

var m = new Map([[1, 'x'], [2, 'y'], [3, 'z']]);
m.forEach(function (value, key, map) {
  console.log(`${value}${key}`);
});

var changes = {
  name: 'virgo',
  age: '27'
}
for (var key in changes) {
  console.log(value = changes[key]);
}