Why Object Keys Is Returns Array Of String Instead Of Array Of Numbers

Have you ever wondered why sometimes when working with object keys in your code, you get an unexpected array of strings instead of an array of numbers? It's a common issue that can be a bit confusing at first, but once you understand the reasons behind it, you'll be able to handle it like a pro. Let's delve into the world of object keys and understand why this happens.

In JavaScript, when you use the Object.keys() method on an object, it returns an array of the object's own enumerable property names. These property names are always strings, even if they represent numeric values. This is because JavaScript automatically converts property names to strings.

So, if you have an object with numeric keys like this:

let obj = { 1: 'one', 2: 'two', 3: 'three' };

And you try to get the keys of this object using Object.keys(obj), you will get an array of strings ['1', '2', '3'], not an array of numbers [1, 2, 3].

This behavior is consistent with how JavaScript handles objects and their keys. The keys of an object are always treated as strings, regardless of whether you define them as numbers or strings.

To work around this behavior and convert the keys back to numbers if needed, you can use the Array.prototype.map() method to parse the keys as numbers. Here's an example:

let obj = { 1: 'one', 2: 'two', 3: 'three' };
let keysAsNumbers = Object.keys(obj).map(Number);

console.log(keysAsNumbers); // Output: [1, 2, 3]

In this code snippet, we first get the keys of the object obj as an array of strings using Object.keys(obj). Then, we use the map() method along with the Number function to convert each string key into a number.

By understanding this nuance of JavaScript's Object.keys() method and how it handles keys as strings, you can write more robust and predictable code when working with objects and their properties.

So, the next time you find yourself scratching your head over why Object.keys() is returning an array of strings instead of numbers, remember that it's all about JavaScript's internal workings and how it treats object keys. With this knowledge in your toolkit, you'll be better equipped to navigate these subtleties and write cleaner, more effective code.