If you're a software developer working with JavaScript, you might have come across the terms `Reflect.ownKeys(obj)` and `Object.keys(obj)`. These can be a bit confusing at first, so let's take a closer look at what sets them apart.
`Reflect.ownKeys(obj)` is a method provided by the `Reflect` object in JavaScript. It returns an array of the target object's property names, including non-enumerable properties and symbols. This means it provides a complete list of all keys, regardless of their enumerability.
On the other hand, `Object.keys(obj)` is a method that returns an array of the target object's own (non-inherited) enumerable property names. This method ignores symbol properties and only includes the keys that can be iterated through using a `for...in` loop or methods like `forEach`.
It's essential to understand that `Reflect.ownKeys(obj)` gives you a more inclusive list of keys, including symbols and non-enumerable properties, while `Object.keys(obj)` focuses solely on the object's own enumerable properties.
Let's illustrate these differences with an example:
const symbolKey = Symbol('key');
const obj = {
prop1: 'Value 1',
prop2: 'Value 2',
[symbolKey]: 'Symbol Key',
};
Object.defineProperty(obj, 'nonEnumProp', {
enumerable: false,
value: 'Non-enumerable Property',
});
console.log(Object.keys(obj));
// Output: ["prop1", "prop2"]
console.log(Reflect.ownKeys(obj));
// Output: ["prop1", "prop2", Symbol(key), "nonEnumProp"]In this example, `Object.keys(obj)` only returns the enumerable properties `prop1` and `prop2`, ignoring the symbol key and the non-enumerable property set using `Object.defineProperty`. On the other hand, `Reflect.ownKeys(obj)` provides a list of all keys, including the symbol key and the non-enumerable property.
When choosing between these methods, consider your specific use case. If you need to work with all types of properties, including symbols and non-enumerable ones, `Reflect.ownKeys(obj)` is the way to go. If you are only interested in the object's own enumerable properties, `Object.keys(obj)` is sufficient.
In summary, `Reflect.ownKeys(obj)` and `Object.keys(obj)` serve different purposes in JavaScript. Understanding their distinctions will help you retrieve the right set of keys based on your requirements when working with objects.