Global timing functions - setInterval

globalTiming.js

/*
 Working with Node.js asynchronously through the use of timing functions.
 The timing functions are:- setTimeout, clearTimeout, setInterval, and clearInterval
 - setTimeout will create a delay of a certain time and then invoke a callback function
 - setInterval will not stop, its like a heartbeat
 - clearInterval & clearTimeout will stop intervals or timeouts that are currently running.
*/

var waitTime = 3000; //waitTime is our total time
var currentTime = 0; //currentTime is the amount of time that we've waited
var waitInterval = 10; //half a sec
var waitingPercentage = 500; // variable to hold the percentage that we've been waiting.
console.log('wait for it');

//func to show our users how long they're waiting as a percentage.
function writeWaitingPercent(p) {
	 // The clearLine function on standard output will clear the last line inside of the Terminal.
	process.stdout.clearLine();
	//cursorTo object will move our cursor back to the beginning of that line.
	process.stdout.cursorTo(0); 
	//process.stdout object to write the percentage that we've been waiting
	process.stdout.write(`waiting ... ${p}%`);
}
//fire interval function like a heartbeat every half second
//interval instance
var interval = setInterval(function(argument) { 
	//update current time (we get accurate indicator of how long we've been waiting).
	currentTime += waitInterval;
	//calculate the percent waited inside of the interval. 
	percentWaited = Math.floor((currentTime/waitTime) * 100);
	writeWaitingPercent(percentWaited);
	//console.log(`waiting ${currentTime/1000} seconds...`);
}, waitInterval);

setTimeout(function() {
	// this will stop the interval from running. It will also exit the application when there is no more running instances.
	clearInterval(interval);
	//use writeWaitingPercent func and send it the percentWaited, which should start out as zero.
	//after we clear the interval, when we're done we will see that we have waited for 100% of the time.
	writeWaitingPercent(100);
	console.log("\n\n done \n\n");
}, waitTime);

process.stdout.write("\n\n");
writeWaitingPercent(percentWaited);