TypeScript Generics All In One

TypeScript Generics All In One

"use strict";

/**
 *
 * @author xgqfrms
 * @license MIT
 * @copyright xgqfrms
 * @created 2022-02-07
 * @modified
 *
 * @description generic
 * @augments
 * @example
 * @link
 *
 */

const log = console.log;

class Person<T> {
  run(value: T) {
    log('run', value);
  }
  static getName(value: T) {
    // Static members cannot reference class type parameters.ts(2302)
  }
}

const p = new Person<number>();
p.run(1);
p.run('1');
// Argument of type 'string' is not assignable to parameter of type 'number'.ts(2345)


// 泛型约束
interface Length {
  length: number,
}

class Test<T extends Length> {
  run(value: T) {
    log('run', value);
  }
  getLength(len: T) {
    log('length =', len, len.length);
  }
}

const t = new Test<string>();
t.run('abc');
t.getLength('abc');
t.getLength(123);
// Argument of type 'number' is not assignable to parameter of type 'string'.ts(2345)

interface Len<T> {
  length: T,
}

class Bug<T extends Len<T>> {
  run(value: T) {
    log('run', value);
  }
  getLength(len: T) {
    log('length =', len, len.length);
  }
}

// const t = new Bug<string>();
// Type 'string' does not satisfy the constraint 'Len<string>'.ts(2344)
// const t = new Bug<string[]>();
/*
Type 'string[]' does not satisfy the constraint 'Len<string[]>'.
  Types of property 'length' are incompatible.
    Type 'number' is not assignable to type 'string[]'.ts(2344)
 */

export {};

Promise

feat

https://github.com/microsoft/TypeScript-Website/issues/2256

(() => {
  const tryLinks = document.querySelectorAll(`[class="playground-link"]`);
  for (let item of tryLinks) {
    item.target = "_blank";
  }
})();

refs

https://www.typescriptlang.org/docs/handbook/generics.html

https://www.typescriptlang.org/docs/handbook/2/generics.html

https://www.typescriptlang.org/play

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