TypeScript Object keys()

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

In this chapter, we will explore the Object.keys() method in TypeScript. This method returns an array of a given object's own enumerable property names (keys). Understanding how to use Object.keys() is useful for iterating over an object's properties.

Definition
Syntax
Examples
Conclusion

1. Definition

The Object.keys() method returns an array of a given object's own enumerable property names (keys). This is useful for iterating over an object's properties.

2. Syntax

Object.keys(obj);

Parameters

obj: The object whose own enumerable property names are to be returned.

Return Value

The method returns an array of the given object's own enumerable property names.

3. Examples

Let's look at some examples to understand how Object.keys() works in TypeScript.

Example 1: Basic Usage

This example shows how to use Object.keys() to get an array of keys from an object.

let person = {
  name: "Ravi",
  age: 25,
  city: "Mumbai"
};

let keys = Object.keys(person);
console.log(keys);
// Output: [ 'name', 'age', 'city' ]

Example 2: Iterating Over Keys

This example shows how to iterate over the keys returned by Object.keys().

let person = {
  name: "Ravi",
  age: 25,
  city: "Mumbai"
};

for (let key of Object.keys(person)) {
  console.log(key);
}
// Output:
// name
// age
// city

Example 3: Using `Object.keys()` with Arrays

This example shows how Object.keys() can be used with arrays.

let fruits = ["apple", "banana", "mango"];
let keys = Object.keys(fruits);
console.log(keys);
// Output: [ '0', '1', '2' ]

Example 4: Converting Keys to Uppercase

This example shows how to convert the keys of an object to uppercase using Object.keys().

let person = {
  name: "Ravi",
  age: 25,
  city: "Mumbai"
};

let uppercaseKeys = Object.keys(person).map(key => key.toUpperCase());
console.log(uppercaseKeys);
// Output: [ 'NAME', 'AGE', 'CITY' ]

Example 5: Handling Non-Enumerable Properties

This example shows how Object.keys() handles non-enumerable properties.

let person = {
  name: "Ravi",
  age: 25
};

Object.defineProperty(person, 'city', {
  value: "Mumbai",
  enumerable: false
});

let keys = Object.keys(person);
console.log(keys);
// Output: [ 'name', 'age' ]

Example 6: Checking if an Object is Empty

This example shows how to check if an object is empty using Object.keys().

let emptyObj = {};
let isEmpty = Object.keys(emptyObj).length === 0;
console.log(isEmpty);
// Output: true

Example 7: Using `Object.keys()` with Nested Objects

This example shows how to use Object.keys() with nested objects.

let person = {
  name: "Ravi",
  address: {
    city: "Mumbai",
    zip: "400001"
  }
};

let keys = Object.keys(person);
console.log(keys);
// Output: [ 'name', 'address' ]

let addressKeys = Object.keys(person.address);
console.log(addressKeys);
// Output: [ 'city', 'zip' ]

4. Conclusion

In this chapter, we explored the Object.keys() method in TypeScript, which is used to return an array of a given object's own enumerable property names (keys). We covered its definition, syntax, parameters, return value, and provided several examples to demonstrate its usage. Understanding how to use Object.keys() is essential for iterating over an object's properties in TypeScript applications.

My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:

Spring Boot + RabbitMQ Course - The Practical Guide

Java Guides

Search This Blog