JS Design Patterns: State, see more at: https://medium.com/p/4a8e1f30b62d

DESIGN_PATTERNS_statePattern.js

/* STATE PATTERN EXAMPLE */

class TVRemoteChannel1State {
  displayStatus() {
    console.log("Hello now watch sports on channel 1");
  }
}

class TVRemoteChannel2State {
  displayStatus() {
    console.log("Hello, watch a serie on channel 2");
  }
}

class TVRemoteChannel3State {
  displayStatus() {
    console.log("Hello, watch the daily news on channel 3");
  }
}

class TVRemoteWithStatePattern {
  constructor() {
    this.channel = 1;
    this.channelInstances = {
      1: new TVRemoteChannel1State(),
      2: new TVRemoteChannel2State(),
      3: new TVRemoteChannel3State(),
    };
  }

  setChannel(channel) {
    this.channel = channel;
  }

  watch() {
    this.channelInstances[this.channel].displayStatus();
  }
}

const TVRemoteInstance1 = new TVRemoteWithStatePattern();

TVRemoteInstance1.setChannel(1);
TVRemoteInstance1.watch();

TVRemoteInstance1.setChannel(2);
TVRemoteInstance1.watch();

TVRemoteInstance1.setChannel(3);
TVRemoteInstance1.watch();