function objectEntries(obj) {
let iter = Reflect.ownKeys(obj)[Symbol.iterator]();
return {
[Symbol.iterator]() {
return this;
},
next() {
let {
done,
value: key
} = iter.next();
if (done) {
return {
done: true
};
}
return {
value: [key, obj[key]]
};
}
};
}
const obj = { first: 'Jane', last: 'Doe' };
for (const [key, value] of objectEntries(obj)) {
console.log(`${key}: ${value}`);
}
// Output:
// first: Jane
// last: Doe
use generators：
function* objectEntries(obj) {
const propKeys = Reflect.ownKeys(obj);
for (const propKey of propKeys) {
yield [propKey, obj[propKey]];
}
}
see more: Iterables and iterators
