JavaScript Fundamentals · Objects · Lesson 19 of 48
Object Basics
Concept
Object Basics
Objects store data as key-value pairs, which makes them great for representing real-world things.
Keys are usually written without quotes when they're valid identifiers, but you can always fall back to bracket notation, especially for keys with spaces or that are stored in a variable.
By the end of this lesson
- Explain the core idea behind Object Basics.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Syntax
const objectName = {
key1: value1,
key2: value2,
};ExampleRunnable
const student = { name: "Alex", age: 20, city: "Tashkent" };
console.log(student.name, student["age"]);Adding and deleting properties
const student = { name: "Alex" };
student.age = 20;
delete student.age;
console.log(student);Self-check before continuing
Without looking at the example, describe what changes when you modify one input in Object Basics. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Create an object representing a course with title, level, and duration properties.
Loading editor…
Console