How can I get an array of object keys in JavaScript?

Question

I'd need to know a way to get all the keys of an object as an array, I tried using the keys method, but it doesn't seem to work.

I've understood from javaTpoint that you could get an array of object's keys using the keys method:
https://www.javatpoint.com/javascript-objects

and with solid understanding on Python dictionary methods it made sense.

But it seems to give an error message and telling that there is no such method as "keys":
https://code.sololearn.com/Wb8243OJxV4q/#js
(In the example I wanted to get the keys (tomato, banaana, potato, strawberry, blueberry) as an array of strings.)

What went wrong?

Answer 1

Use it this way:

const myObject = {
question: "everything",
answer: 42
}

const keys = Object.keys(myObject);

Answer 2

Supplementing to the solution which Burey provided, I am hereby providing an explanation :

Because for JavaScript class methods, there are two types : Class methods and prototypical methods, take String methods charCodeAt and fromCharCode as example:

For String.prototype.charCodeAt, the function is inherited by its instance, and its returned value varies among different String instances, so we have to call the charCodeAt with an instance bound.
https://www.sololearn.com/post/143486/?ref=app

For String.fromCharCode, the function returns a character based on its numeric argument, and is universal over different string instances, so we call by referencing fromCharCode under the class (String).
https://www.sololearn.com/post/143917/?ref=app

https://code.sololearn.com/WKKkpq0efxai/?ref=app

For keys, it is an Objects class method, so we call by prefixing its class (Objects).

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

P. S. Mozilla Doc is better as ref

Answer 3

शंकर भाई गुजरात