How to Remove a Key from TypeScript Object ?

In TypeScript, objects are mutable, which means you can modify them by adding, updating, or removing properties. Removing a key from an object involves either creating a new object without the specified key or using certain built-in methods to achieve the desired result.

Below are the approaches used to remove a key from a TypeScript object:

Approach 1: Using spread operator

This approach involves creating a new object that excludes the key you want to remove. The spread operator (...) is used to copy the existing properties of the object into a new object, excluding the specified key.

Syntax:

const modifiedObject = { ...originalObject, [keyToRemove]: undefined };

Example: In this example, year is removed from originalObject, and the result is stored in newObject.

interface MyObject {
    [key: string]: any;
}

const originalObject: MyObject = 
    { name: 'GFG', year: 2024, city: 'Noida' };
console.log("Original Object");
console.log(originalObject);
const keyToRemove: string = 'year';
console.log("After key removal");
const { [keyToRemove]: removedKey, ...newObject } = 
    originalObject;

console.log(newObject);

Output:

Original Object
{ name: 'GFG', year: 2024, city: 'Noida' }
After key removal
{ name: 'GFG', city: 'Noida' }

Approach 2: Using delete keyword

To remove a key from a TypeScript object, you can use the delete operator or create a new object without the specified key.

Syntax:

delete objectName[keyToRemove];

Example: In this example, the age property is removed from the person object using the delete keyword.

interface Person {
    name: string;
    age: number;
    city: string;
}

const person: Person = 
    { name: 'Alice', age: 30, city: 'London' };

// Ensuring keyToRemove is a valid key of Person
const keyToRemove: keyof Person = 'age'; 
console.log("Original Object");
console.log(person);

// Deleting the specified key from the object
delete person[keyToRemove]; 

console.log("After key removal");
console.log(person);

Output:

Original Object
{ name: 'Alice', age: 30, city: 'London' }
After key removal
{ name: 'Alice', city: 'London' }

Approach 3: Using Object.assign()

To remove a key from an object using Object.assign(), we create a new object by copying all properties from the original object except for the specified key.

Example: In this example we creates a TypeScript object, removes a specified key using Object.assign() and delete, and logs both the original and modified objects. It's correct but could benefit from using more TypeScript-friendly methods.

interface MyObject {
    [key: string]: any;
}

const originalObject: MyObject = { name: 'GFG', year: 2024, city: 'Noida' };
console.log("Original Object:");
console.log(originalObject);

const keyToRemove: string = 'year';

// Create a new object without the specified key
const newObject = Object.assign({}, originalObject);
delete newObject[keyToRemove];

console.log("After key removal:");
console.log(newObject);

Output:

Original Object:
{ name: 'GFG', year: 2024, city: 'Noida' }
After key removal:
{ name: 'GFG', city: 'Noida' }

Approach 4: Using Object destructuring and rest syntax

In this approach, we leverage object destructuring along with the rest syntax to create a new object that excludes the specified key. We use object destructuring to extract all properties of the original object except the one we want to remove, and then use the rest syntax to collect these properties into a new object.

Example: In this example, we'll use object destructuring and rest syntax to remove the key "year" from the original object.

interface MyObject {
    [key: string]: any;
}

const originalObject: MyObject = { name: 'GFG', year: 2024, city: 'Noida' };
console.log("Original Object:");
console.log(originalObject);

const keyToRemove: string = 'year';

// Using object destructuring and rest syntax to remove the specified key
const { [keyToRemove]: removedKey, ...newObject } = originalObject;

console.log("After key removal:");
console.log(newObject);

Output

Original Object:
{ name: 'GFG', year: 2024, city: 'Noida' }
After key removal:
{ name: 'GFG', city: 'Noida' }

Approach 5: Using Object.entries() and Object.fromEntries()

This approach involves converting the object into an array of key-value pairs using Object.entries(), filtering out the key you want to remove, and then converting the array back into an object using Object.fromEntries(). This method is useful for creating a new object without modifying the original object.

Syntax:

const modifiedObject = Object.fromEntries(Object.entries(originalObject).filter(([key]) => key !== keyToRemove));

Example: In this example, the key year is removed from originalObject, and the result is stored in newObject.

interface MyObject {
  [key: string]: any;
}

const originalObject: MyObject = { name: 'GFG', year: 2024, city: 'Noida' };
console.log("Original Object:");
console.log(originalObject);

const keyToRemove: string = 'year';

// Using Object.entries and Object.fromEntries to remove the specified key
const newObject = Object.fromEntries(Object.entries(originalObject).filter(([key]) => key !== keyToRemove));

console.log("After key removal:");
console.log(newObject);

Original Object:
{ name: 'GFG', year: 2024, city: 'Noida' }
After key removal:
{ name: 'GFG', city: 'Noida' }