javascript の for...of と for..in のメモ

'use strict';

const any = (arr) => {
  for (let value of arr) {
    if (value) {
      return true;
    }
  }
  return false;
};

console.log(any([false, false, false]));
console.log(any([false, true, false]));
//=> false
//=> true


const object = {foo: [false, false, false], bar: [false, false, true]};

for (let key in object) {
  console.log(key);
  console.log(object[key]);
}
//=> foo
//=> [ false, false, false ]
//=> bar
//=> [ false, false, true ]

• 配列は for...of
• オブジェクトは for...in

参考

• for...of - JavaScript | MDN
• for...in - JavaScript | MDN