Javascript Tutorial: Converting an Object to an Array

Converting Object to an Array

Finally, with ES2017, it’s official now! We have 3 variations to convert an Object to an Array 🎊

Array has an array of methods (sorry, bad pun 😝). So by converting the object into an array, you have access to all of that. Woohoo 🥳

const zoo = {
  lion: '🦁',
  panda: '🐼'
};

Object.keys(zoo)
// ['lion', 'panda']

Object.values(zoo)
// ['🦁', '🐼']

Object.entries(zoo)
// [ ['lion', '🦁'], ['panda', '🐼'] ]

Time for a story…

Ancient times

Long long ago, in a far far galaxy, looping over Objects was not so easy. Okay, I’m exaggerating a bit 😅. But I remember whenever I needed to convert an object into an array, I had to do something like this.

var numbers = {
  one: 1,
  two: 2
};

var keys = [];

for (var number in numbers) {
  if(numbers.hasOwnProperty(number)){
    keys.push(number)
  }
}

keys; // [ 'one', 'two' ]

I always was so angry and wished there was a better way…

ES6 - Object.keys

And then ES6 happened! My life changed! We finally have an easier way 🥳

Now, there was a built-in method that quickly turns all the keys in my object into an array:

const numbers = {
  one: 1,
  two: 2
}

Object.keys(numbers);
// [ 'one', 'two' ]

Life was beautiful! But then I became angry again. Why can I only extract the keys, I want my values too! Humans always want more don’t we 😂 And then ES2017 rolled in…

Object.values

Hi, I’m ES2017 and I grant you all your wish 🧞‍♀️. you can now easily extract the values into an array with one method.

const numbers = {
  one: 1,
  two: 2
}

Object.values(numbers);
// [ 1, 2 ]

Object.entries

But ES2017 didn’t stop there. It gave me more! I grant you BOTH keys and values now, so stop being angry. I was blown away. It turned my frown upside down 😆

const numbers = {
  one: 1,
  two: 2
}

Object.entries(numbers);
// [ ['one', 1], ['two', 2] ]

Booya 👊

Object.entries + Destructuring

But then I’m like…nested array 🤨. C’mon, that’s not fun to work with. ES6 swoops in and like, don’t worry! That’s why I gave you destructuring!

const numbers = {
  one: 1,
  two: 2
}

const objectArray = Object.entries(numbers);

objectArray.forEach(([key, value]) => {
  console.log(key); // 'one' -> 2
  console.log(value); // 1 -> 2
})

ES6, that’s why you are simply the best 💛

End of story

Hope you enjoyed my code story-telling time 😂

Now go out there and have some fun with all these amazing Object methods 😊

Browser Support

Object.keys has the best support. When I say best, it means it supports Internet Explorer 😆. The other, Object.values and Object.entries, unfortunately, don’t support Internet Explorer. Luckily, polyfill exists which can improve support.

Polyfill

• MDN: Object.keys
• MDN: Object.values
• MDN: Object.entries

But wait, there’s more…

Your next question might be, now how do I convert the array back to an object. Don’t worry, that’s covered. There is a new method called Object.fromEntries. It essentially is the opposite of Object.entries.

const array = [
  [ 'one', 1 ],
  [ 'two', 2 ]
];

Object.fromEntries(array);
// { one: 1, two: 2 }

MDN: Object.fromEntries

Note: This is extremely new, so support will be limited. Keep this in your knowledge box, but maybe wait a bit longer before you put it in your actual toolbox 🧰

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