Private keyword The private keyword in TypeScript is a compile time annotation. It tells the compiler that a property should only be accessible inside that class: class PrivateKeywordClass { private value = 1; } const obj = new PrivateKeywordClass(); obj.value // compiler error: Property ‘value’ is private and only accessible within class ‘PrivateKeywordClass’. However compile … Read more
No, this doesn’t look to be possible. From the proposal FAQ: Why doesn’t this[‘#x’] access the private field named #x, given that this.#x does? This would complicate property access semantics. Dynamic access to private fields is contrary to the notion of ‘private’. E.g. this is concerning: class Dict extends null { #data = something_secret; add(key, … Read more
Initializing properties directly on a class in ES6 is not possible, only methods can currently be declared in this way. Same rules stand in ES7 as well. However, it is a proposed feature that might come after ES7 (currently in stage 3). Here is the official proposal. Additionally, the syntax the proposal is suggesting is … Read more
It looks like it is a problem to hand over a string which has a special meaning. If really necessary, you evaluate a string. class Test { #field = ‘foo’; get field() { return eval(‘this.’ +’#field’); } } console.log(new Test().field)
ESLint v8 now supports static class properties natively: https://eslint.org/blog/2021/10/eslint-v8.0.0-released parserOptions ecmaVersion should be set to 13, 2022, or “latest” to enable the support. Add this to your .eslint.(cjs | json | js) { parserOptions: { ecmaVersion: 2022, } }
Simply put, the reason to use this is ease of understanding the code. Without class field declarations, you would do something like: class Person { constructor() { this.firstName = “Mike”; this.lastName = “Patel”; this.getName = () => { return this.firstName + ” ” + this.lastName; }; } } var p = new Person(); console.log(p.firstName); // … Read more
If you want to use experimental features (such as arrows as class methods) you need to use babel-eslint as a parser. Default parser (Espree) doesn’t support experimental features.
You make “public static field” using accessor and a “static” keyword: class Agent { static get CIRCLE() { return 1; } static get SQUARE() { return 2; } } Agent.CIRCLE; // 1 Looking at a spec, 14.5 — Class Definitions — you’d see something suspiciously relevant 🙂 ClassElement[Yield] : MethodDefinition[?Yield] static MethodDefinition[?Yield] ; So from … Read more
There are differences between all 3 versions. This differences are in 3 areas: Who is this at runtime Where the function is assigned What is the type of this in typescript. Lets start with where they work just the same. Consider this class, with a class field: class Greeter { constructor(private x: string) { } … Read more
They are roughly equivalent. The significant difference is that the initializer in the second example is executed before constructor. The second approach uses class fields proposal. It is not a part of ECMAScript standard yet so you need to set up transpiler properly to use the second approach. UPD Take a look at Babel output … Read more