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ECMAScript Private Fields in TypeScript 3.7
The document discusses the conformance of TypeScript 3.7 with the ECMAScript standard, specifically focusing on private fields in classes. It includes examples of class definitions with private fields, the implementation status across different browsers, and related proposals by TC39. The document highlights the syntax for defining private fields and their usage, as well as links to relevant resources and feedback channels.
ECMAScript Private Fields in TypeScript 3.7
- 1. TypeScript 3.7 Language StandardConformance ECMAScript Private Fields
- 2. Private Fields • Preventusers from relying on internals which may change • Specified by TC39 (Technical Committee 39) • Authors: Daniel Ehrenberg (Igalia), Jeff Morrison (Facebook) • Merged with class field declarations proposal • Stage 3 (Strawperson, Draft, Candidate, Finished) • Awaits feedback: https://github.com/tc39/proposal-class-fields • Available online: https://tc39.es/proposal-class-fields/ 2019/12/17
- 3. ECMAScript Syntax class Point{ #x; #y; constructor(x, y) { this.#x = x; this.#y = y; } equals(point) { return this.#x === point.#x && this.#y === point.#y; } } const p1 = new Point(1, 2); const p2 = new Point(1, 2); p1.equals(p2); // true 2019/12/17
- 4. TypeScript Counterpart class Point{ private x: number; private y: number; constructor(x: number, y: number) { this.x = x; this.y = y; } equals(point: Point) { return this.x === point.x && this.y === point.y; } } const p1 = new Point(1, 2); const p2 = new Point(1, 2); p1.equals(p2); // true 2019/12/17
- 5. Implementation Status • Introducedin Chrome 74 • “SyntaxError: private fields are not currently supported” in Firefox 71 • Expected with TypeScript 3.7 https://github.com/microsoft/TypeScript/issues/33352 2019/12/17
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