How to use forever-monitor in node

/* monitor.js */
var forever = require('forever-monitor');
var time = require('./time');

var maxRestart = 20;

var now = time.getFormString();

var child = new (forever.Monitor)('app.js', {
    max: maxRestart,
    silent: true,
    args: [],
    'logFile':'log/'+now+'.log', 
    'outFile':'./'+now+'.out', 
    'errFile':'./'+now+'.err'
});

child.on('restart', function() {
    console.log(time.getKoreaString() + ', forever restart');
});

child.on('exit', function () {
    console.log(time.getKoreaString() + ', app.js has exited after'+ maxRestart+' restarts');
});

child.start();