Rx.Observable.log()

custom subject.png

observable-log.js

Rx.Observable.prototype.log = (function(){
  let count =  0;
  return function log(optionalName) {
    let str = `Observable ${optionalName || ++count}:\t`;
    return this.do({
      next: v => str += `--${v}`,
      error: () => console.log(str + "--#"),
      complete: () => console.log(str + "--|"),
    });
  };
})();

observer-logger.js

logger = (() => {
  let count = 0;
  return (name = ++count) => {
    const log = m => console.log.bind(console, `Observer ${name}`, m);
    return {
      next: log("value"),
      error: log("error"),
      complete: log("complete"),
    };
  }
})();

subjects.png

time-logger.js

timeLogger = (() => {
  let count = 0;
  const ms = (s) => String(s+' ms').padEnd(7);
  return (name = ++count) => {
    let firstDT = null;
    let lastDT = null;
    let str = `Observer ${name}:\n`;
    const log = (m, print) => {
      const newDT = Date.now();
      const msDiff = lastDT ? newDT - lastDT : 0;
      firstDT || (firstDT = newDT);
      lastDT = newDT;
      str += `\t• ${ms(lastDT-firstDT)}\t[ Δ ${ms(msDiff)} ]\t${m}\n`;
      print && console.log(str);
    };
    log('subscribed');
    return {
      next: v => log(`value: ${v}`),
      error: e => log(`error: ${e}`, true),
      complete: () => log('complete', true),
    };
  }
})();