How do I remove a key from a JavaScript object?

Removing a key from a JavaScript object is a common task when cleaning up data or updating objects dynamically. JavaScript provides multiple ways to achieve this, each with slightly different use cases and behaviors.

The most straightforward method is using the delete operator. For example:

let user = { name: "Alex", age: 25, city: "New York" };  

delete user.age;  

console.log(user); // { name: "Alex", city: "New York" }

This removes the age property from the object permanently.

Another modern approach is object destructuring combined with the rest operator, which creates a new object without the unwanted key:

const { age, ...updatedUser } = user;  

console.log(updatedUser); // { name: "Alex", city: "New York" }

This is useful if you want to avoid mutating the original object.

Here are some key points to consider:

• delete operator: Simple and direct, but mutates the original object.
  
• Destructuring + rest operator: Creates a new object without the key, preserving immutability (often preferred in React or functional programming).
  
• Utility libraries: Tools like Lodash provide methods (_.omit) for more advanced key removal in larger projects.
  
• Performance: While delete works fine in most cases, it can impact performance if used heavily inside loops, as it alters the object’s shape.
  

In short, the method you choose depends on whether you want to mutate the original object or create a new one. For quick deletions, delete works well; for cleaner, immutable patterns, destructuring is often the better choice.