grab.signal.js

grab.signal.js

/* @flow */
class Signal {
  value: any;
  fns: Array<Function>

  constructor(value: any) {
    this.value = value;
    this.fns = [];
  }

  update(value: any): void {
    this.value = value;
    for (let i = 0; i < this.fns.length; i++) {
      const currentValue = this.fns[i](this.value);
      this.value = currentValue;
    }
  }

  next(fn: Function): Signal {
    this.fns.push(fn);
    return this;
  }

  map(fn: Function): Signal {
    this.fns.push(arr => arr.map(fn));
    return this;
  }

  filter(fn: Function): Signal {
    this.fns.push(arr => arr.filter(fn));
    return this;
  }
}


const foo = new Signal();

const bar = foo.map(i => i * 2)
  .filter(a => a % 2 === 0)
  .next(console.log)

bar.update([1, 2]);