for-of-able.js

Object.prototype[Symbol.iterator] = function* () {
    for (const key of Object.keys(this)) {
        yield this[key]
    }
}

var obj = {
    'mark': 32,
    'alex': 19,
    'mary': 25
}

console.log('can iterate keys')
for (let key in obj) {
    console.log('key:', key)
}

console.log('can iterate values')
for (let value of obj) {
    console.log('value:', value)
}