How does 'this' work in different contexts?

this is determined by how a function is called:

• Global → window / undefined (strict)
• Method call → the object before the dot
• new → the newly created object
• call/apply/bind → whatever you pass
• Arrow function → outer lexical scope
• Event listener → the element that fired

const obj = { val: 42, getVal() { return this.val; } };
const fn = obj.getVal;
fn();          // undefined — lost context!
fn.call(obj);  // 42 — restored