What does get mean in this ES6 class? How do I reference this function? How should I use it?
class Polygon { constructor(height, width) { this.height = height; this.width = width; } get area() { return this.calcArea() } calcArea() { return this.height * this.width; }
}3 Answers
It means the function is a getter for a property.
To use it, just use it's name as you would any other property:
'use strict'
class Polygon { constructor(height, width) { this.height = height; this.width = width; } get area() { return this.calcArea() } calcArea() { return this.height * this.width; }
}
var p = new Polygon(10, 20);
alert(p.area);Summary:
The get keyword will bind an object property to a function. When this property is looked up now the getter function is called. The return value of the getter function then determines which property is returned.
Example:
const person = { firstName: 'Willem', lastName: 'Veen', get fullName() { return `${this.firstName} ${this.lastName}`; }
}
console.log(person.fullName);
// When the fullname property gets looked up
// the getter function gets executed and its
// returned value will be the value of fullnameIt is getter, same as Objects and Classes in OO JavaScript. From the MDN Docs for get:
The
getsyntax binds an object property to a function that will be called when that property is looked up.
