[发布-订阅模式] #Javascript #设计模式

onfire.js

export default class OnFire {
  constructor() {
    this.es = {};
  }

  on(evt, cb, once = false) {
    if (!this.es[evt]) {
      this.es[evt] = [];
    }

    this.es[evt].push({ cb, once });
  }

  once(evt, cb) {
    this.on(evt, cb, true);
  }

  off(evt, cb) {
    // 清空
    if (evt === undefined) {
      this.es = {};
      return;
    }

    if (cb === undefined) {
      delete this.es[evt];
      return;
    }

    const ls = this.es[evt] || [];
    ls.splice(ls.findIndex(l => l.cb === cb), 1);
  }

  fire(evt, ...args) {
    const ls = this.es[evt] || [];
    let j = ls.length;
    for (let i = 0; i < j; i++) {
      const { cb, once } = ls[i];
      cb.apply(this, args);
      once && this.off(evt, cb);
    }
  }

  // cname of fire
  emit(evt, ...args) {
    this.fire(evt, ...args);
  }
}