os-monitor/lib/throttle.js

simple OS monitoring for Node.js

"use strict";
// Throttle function from Underscore.js 1.13.8
// https://underscorejs.org/#throttle
// (c) 2009-2026 Jeremy Ashkenas, Julian Gonggrijp, and DocumentCloud and Investigative Reporters & Editors
// Underscore may be freely distributed under the MIT license.

Object.defineProperty(exports, "__esModule", { value: true });

const now = Date.now || function() {
  return new Date().getTime();
};

// Returns a function, that, when invoked, will only be triggered at most once
// during a given window of time. Normally, the throttled function will run
// as much as it can, without ever going more than once per `wait` duration;
// but if you'd like to disable the execution on the leading edge, pass
// `{leading: false}`. To disable execution on the trailing edge, ditto.
function throttle(func, wait, options) {
  var timeout, context, args, result;
  var previous = 0;
  if (!options) options = {};

  var later = function() {
    previous = options.leading === false ? 0 : now();
    timeout = null;
    result = func.apply(context, args);
    if (!timeout) context = args = null;
  };

  var throttled = function() {
    var _now = now();
    if (!previous && options.leading === false) previous = _now;
    var remaining = wait - (_now - previous);
    context = this;
    args = arguments;
    if (remaining <= 0 || remaining > wait) {
      if (timeout) {
        clearTimeout(timeout);
        timeout = null;
      }
      previous = _now;
      result = func.apply(context, args);
      if (!timeout) context = args = null;
    } else if (!timeout && options.trailing !== false) {
      timeout = setTimeout(later, remaining);
    }
    return result;
  };

  throttled.cancel = function() {
    clearTimeout(timeout);
    previous = 0;
    timeout = context = args = null;
  };

  return throttled;
}

module.exports.throttle = throttle;