#6 most askedVery commonMediumthis & prototypes

How does `this` work?

🏢 Asked in real interviews

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What decides the value of this in JavaScript? Predict the output.

🔮 Predict the output

class User {
  constructor() { this.name = "Ada"; }
  regular() { return this?.name; }
  arrowInside() { return [1].map(() => this.name)[0]; }
  plainInside() { return [1].map(function () { return this?.name; })[0]; }
}
const u = new User();
const loose = u.regular;
console.log(u.regular(), loose(), u.arrowInside(), u.plainInside());

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