Page 181 - JavaScript

}

// you can also use any javascript expression

// this one is just a string, and could also be defined with simply add()
["add"](a, b) {
return a + b;
}

// this one is dynamically evaluated
[1 + 2]() {
return "three";
}
}

let MazdaMPV = new Car("Mazda", "MPV");
MazdaMPV.add(4, 5); // 9
MazdaMPV[3](); // "three"
MazdaMPV[METADATA](); // { make: "Mazda", model: "MPV" }

Methods

Methods can be defined in classes to perform a function and optionally return a result.
They can receive arguments from the caller.

class Something {
constructor(data) {
this.data = data
}

doSomething(text) {
return {
data: this.data,
text
}
}
}

var s = new Something({})
s.doSomething("hi") // returns: { data: {}, text: "hi" }

Managing Private Data with Classes

One of the most common obstacles using classes is finding the proper approach to handle private
states. There are 4 common solutions for handling private states:

Using Symbols

Symbols are new primitive type introduced on in ES2015, as defined at MDN

A symbol is a unique and immutable data type that may be used as an identifier for
object properties.

When using symbol as a property key, it is not enumerable.

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