How does the this keyword work in JavaScript?

Question

How does the this keyword work in JavaScript?

Answer

this refers to the execution context — the object that owns the current function call.
Its value depends on how the function is called, not where it’s defined.

console.log(this); // Window (in browser)

function show() {
  console.log(this);
}
show(); // Window or undefined (strict mode)

const obj = { show };
obj.show(); // obj

const arrow = () => console.log(this);
arrow(); // inherits from lexical scope

Real-World Example

In React class components, this is used to access state and methods — but in functional components, we use hooks to avoid it.

Quick Practice

What will this point to in each case?

function say() {
  console.log(this);
}
say();
new say();

Summary

this depends on how a function is called — context is everything.