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Singleton

Singleton Use Case
  • Redux/VueX global store.
  • Window 对象.
  • 全局配置.
  • 全局缓存.
  • 线程池.
  • 内存池.

Class Singleton​

class Singleton {
  constructor() {
    const instance = this.constructor.instance
    if (instance)
      return instance
    this.constructor.instance = this
  }

  say() {
    console.log('Saying...')
  }
}

class Singleton {
  private static instance: Singleton
  private constructor() {}

  public static getInstance() {
    if (!Singleton.instance)
      Singleton.instance = new Singleton()

    return Singleton.instance
  }

  someMethod() {}
}

const instance = Singleton.getInstance()

Closure Singleton​

const createLoginLayer = (function (creator) {
  let singleton

  return function () {
    if (!singleton)
      singleton = creator()
    return singleton
  }
})(loginCreator)