Setter-setter and setter

callbag.js

const LIMIT = 10000;

let sinkRef, sending, completed, sourceDisposed;

const source = (type, data) => {
  if (sourceDisposed || completed) {
    return;
  }
  
  if (type === 0) {
    sinkRef = data;
    return;
  }
  
  if (typeof sinkRef !== 'function') {
    // make sure the source is greeted before sending 1/2 signals
    return;
  }
  
  if (type === 1) {
    // Avoid stackoverflow errors
    while (sending = !sending) {
      if (data < LIMIT) {
        sinkRef(1, data++); // setter
      } else {
        completed = true;
        sinkRef(2); // setter
      }
    }
    return;
  }
  
  if (type === 2) {
    sourceDisposed = true;
  }
};

let sourceRef, sinkDisposed;

const sink = (type, data) => {
  if (sinkDisposed) {
    return;
  }

  if (type === 0) {
    sourceRef = data;
    return;
  }
  
  if (typeof sourceRef !== 'function') {
    // make sure the sink is greeted before sending 1/2 signals
    return;
  }
  
  if (type === 1) {
    console.log(`Next(${data})`);
    sourceRef(1, data); // setter
    return;
  }
  
  if (type === 2) {
    data == null ? console.log('Done()') : console.log(`Error(${data})`);
    sinkDisposed = true;
  }
};

// Handshake
source(0, sink); // Source: setter-setter, Sink: callback (listener)
sink(0, source); // Sink: setter-setter, Source: callback (listener)

// Start conversation
source(1, 0); // Source: setter

/*
Logs:
Next(0)
Next(1)
...
Next(9999)
Done()
*/