Use case for methods defined in constructor

Asked Dec 05 '18 at 20:59

Active Dec 05 '18 at 20:59

Viewed 24 times

One could write a greet method for instances of a Person object in at least two ways:

function Person(name) {
  this.name = name
  this.greet = () => {
    console.log(`hello, my name is ${this.name}`)
  }
}

// or
function Person(name) {
  this.name = name
}

Person.prototype.greet = function() {
  console.log(`hello, my name is ${this.name}`)
}

It's common best practice to extend an objects prototype rather than define methods within the constructor.

Is there ever a use case for defining instance methods in a constructor function?

asked Dec 05 '18 at 20:59

Andrew Kim

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Yes, when these methods need some "private" variable that is only available in the constructor. #[tag:closures] – Thomas Dec 05 '18 at 21:01
The huge difference is that your constructor-created `greet` is an arrow function that closes over the `this` instance. – Bergi Dec 05 '18 at 21:07
like.. meta programming? – Andrew Kim Dec 05 '18 at 21:07
to be fair, i need to give this duplicate question a heavy read, context gets twisted up for me when i read into it – Andrew Kim Dec 05 '18 at 21:08

Use case for methods defined in constructor

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