A JavaScript function to log messages to the console periodically.

JS Log Periodically

/**
 * Periodically log a message to the JavaScript console.
 *
 * This is useful for logging things in loops; it avoids being overwhelmed by
 * an unstoppable barrage of similar log messages. Example calls:
 *
 * # Log "message" to the console no more than every 500ms.
 * logPeriodically('message', 500);
 * # Log "message" as an error no more than every 500ms.
 * logPeriodically('message', 500, console.error);
 * # Provide an ID if you want to keep track of multiple logging calls.
 * logPeriodically('draw message', 500, 'draw');
 * logPeriodically('update message', 500, 'update');
 * # You can also provide both an ID and a logging function.
 * logPeriodically('draw message', 500, 'draw', console.error);
 * logPeriodically('update message', 500, 'update', console.log);
 *
 * @param ...
 *   An arbitrary number of arguments to pass to the loggging function.
 * @param freq
 *   The minimum amount of time in milliseconds that must pass between messages
 *   with the same identifier before logging the next one. To only log
 *   something once, pass Infinity to this parameter.
 * @param id
 *   (Optional) An identifier for the log message. Log messages with the same
 *   identifier will be logged no more often than the amount of time specified
 *   by the freq parameter.
 * @param func
 *   (Optional) The logging function to use. Defaults to console.log.
 */
function logPeriodically() {
  if (arguments.length < 2) {
    return;
  }
  var freq = 0, id = '_', func = Array.prototype.pop.call(arguments);
  if (typeof func == 'number') {
    freq = func;
    func = console.log || function() {};
  }
  else if (typeof func == 'string') {
    freq = Array.prototype.pop.call(arguments);
    id = func;
    func = console.log || function() {};
  }
  else if (typeof func == 'function') {
    id = Array.prototype.pop.call(arguments);
    if (typeof id == 'string') {
      freq = Array.prototype.pop.call(arguments);
    }
    else if (typeof id == 'number') {
      freq = id;
      id = '_';
    }
  }
  if (typeof this.lastLogged == 'undefined') {
    this.lastLogged = {};
  }
  if (typeof this.lastLogged[id] == 'undefined') {
    this.lastLogged[id] = 0;
  }
  var now = Date.now();
  if (now > this.lastLogged[id] + freq) {
    this.lastLogged[id] = now;
    func.apply(func, arguments);
  }
}