Wrap a generator to log its output

log-advice.js

/**
 * Logs generated values and re-yields them. Keeps the same
 * signature and behavior as the wrapped geneator.
 *
 * @example const myGenerator = logAdvice(function*(…){…})
 *
 * @param {GeneratorFunction} generator The generator to wrap
 * @param {Function} [filter = () => true] Only log yielded values that evaluate to `true`
 * @returns {GeneratorFunction} A generator that can be called exactly like the one passed in
 */
function logAdvice(generator, filter = () => true) {
  return function* logAdviceWrapper(...rest) {
    for (const y of generator(...rest)) {
      if (filter(y)) {
        console.log(y);
        // Get stacktrace
        // console.log(new Error().stack);
      }
      yield y;
    }
  };
}