The Modern JavaScript Collection by Aurelio De Rosa

Author:Aurelio De Rosa [Various]
Language: eng
Format: epub
Publisher: SitePoint
Published: 2017-08-08T23:00:00+00:00

ESnext Class Fields

The class fields proposal allows properties to be initialized at the top of a class:

class MyClass { a = 1; b = 2; c = 3; }

This is equivalent to:

class MyClass { constructor() { this.a = 1; this.b = 2; this.c = 3; } }

Initializers are executed before any constructor runs (presuming a constructor is still necessary).

Static Class Fields

Class fields permit static properties to be declared within the class. For example:

class MyClass { x = 1; y = 2; static z = 3; } console.log( MyClass.z ); // 3

The inelegant ES6 equivalent:

class MyClass { constructor() { this.x = 1; this.y = 2; } } MyClass.z = 3; console.log( MyClass.z ); // 3

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