emulates loadavg for windows platforms

node-windows-loadavg.js

var lastCpus = [];
var lastTimestamp = 0;
const { performance } = require('perf_hooks');

function AvgList(limit){
  this.measures = [];
  this.totalTime = 0;
  this.limit = limit;
  this.push = function(measure){
    if ((this.totalTime + measure.delta) > this.limit) {
      console.log("samples exceed limit");
      var delta = measure.delta;
      this.measures = this.measures.filter((filtermeasure) => {
        if (delta > 0) {
          delta -= filtermeasure.delta;
          this.totalTime -= filtermeasure.delta;
          return false;
        }else{
          return true;
        }
      });
    }
    this.measures.push(measure);
  }
  this.getAvg = function(period){
    if (!period) {
      period = this.limit;
    }
    var count = 0;
    var total = 0;
    var totalTime = 0;
    for (var i = this.measures.length - 1; i >= 0; i--) {
      var measure = this.measures[i];
      if ((totalTime + measure.delta) < period) {
        count++;
        total += measure.avg;
        totalTime += measure.delta;
      }else{
        var scale = (period-totalTime) / measure.delta;
        count += scale;
        total += measure.avg*scale;
        totalTime += measure.delta*scale;
        break;
      }
    }
    return total/count;
  }
}

var avglist = new AvgList(10*60*1000);/*hold up to 10 minutes of data*/

function cpuAvg(cpus){
  var avg = 0;
  for (var i = 0; i < cpus.length; i++) {
    var deltaTimes = {
      total: 0
    };
    for (key in cpus[i].times) {
      deltaTimes[key] = cpus[i].times[key] - lastCpus[i].times[key];
      deltaTimes.total += deltaTimes[key];
    }
    if (deltaTimes.total>0) {
      avg += (deltaTimes.total - deltaTimes.idle) / deltaTimes.total;
    }
  }
  return avg;
}

function loadavg(){
  var cpus = this.cpus();
  var avg = cpuAvg(cpus);
  lastCpus = cpus;
  var now = performance.now();
  avglist.push({avg: avg, delta: now-lastTimestamp});
  lastTimestamp = now;
  return [parseFloat(avglist.getAvg(60*1000).toFixed(2)), parseFloat(avglist.getAvg(5*60*1000).toFixed(2)), parseFloat(avglist.getAvg().toFixed(2))]
}

function bind(os){
  os.loadavg = loadavg;
  lastCpus = os.cpus();
  lastTimestamp = performance.now();
}

module.exports = bind;

example

var os = require('os');
if (os.platform() == "win32") {
  require('./windows-loadavg.js')(os);
}
console.log(os.loadavg());