TM-Timer

A simple count-down Timer class, based on TM-Ticker (no GUI)

Installation

$ npm install tm-timer

import Timer from 'tm-timer';
// or
const Timer = require('tm-timer');

TL;DR

Jump to API

Create:

// construct & config
const t = new Timer(duration, finalCallback)
 
// or just construct (and config later)
const t = new Timer()

Config:

t.set(duration)
t.whenDone(finalCallback)
t.onTick(tickHandler)

Use:

now is optional

 t.start(now)

 t.getTimeLeft()

 t.stop(now)

 t.reset(now)

 t.destroy()

API

---

Constructor

const t = new Timer(duration, finalCallback);

• duration [number, optional*]
  * Required to start. optional at construction.
  Countdown in milliseconds. Pass null to set the callback alone.

• finalCallback [function, optional]
  The function you want to call when countdown is over.

Example:

const fiveMinutes = 5 * 60 * 1000;
 
const t = new Timer(fiveMinutes, () => {
    console.log('Game Over');
});

Configuration

A Timer instance won't tick unless it has a duration.

You can set the timer's duration and final callback on construction or later with the following methods which are very self explanatory:

const myTimer = new Timer();
 
myTimer.set(fiveMinutes)
myTimer.whenDone(finalCallback)
myTimer.onTick(myTickHandler)

.set(duration)

• duration [number, required]
  Set the total time in milliseconds to count down to.

const fiveMinutes = 5 * 60 * 1000;
 
myTimer.set(fiveMinutes);

.whenDone(finalCallback)

• finalCallback [function, required]
  Runs when timer finishes. Gets no arguments.

myTimer.whenDone(() => {
    console.log("Time's Up!");
});

.onTick(callback)

As the timer counts down, it ticks every 500ms (twice every second).
Use when you can bind a tick handler function.
The first tick happens on start, synchronously, before any timeout.

• callback [function, optional]
  The callback function recieves two arguments:

  1. isBigTick [boolean]
     Equals true on "big" ticks (a whole second: 0, 1000, 2000, 3000 etc.)
     Equals false on "small" ticks (half a second: 500, 1500, 2500, 3500 etc.)
     For example, you could update your clock's digits on big ticks and blink the clock's colons on small ticks (04:20).

  2. timeLeft [number]
     Time left in milliseconds.

Example:

myTimer.onTick((isBigTick, timeLeft) => {
    console.log(isBigTick); //  | true | false | true | false |...
    console.log(timeLeft);  //  | 5000 | 4500  | 4000 | 3500  |...
 
    /*
    * NOTE:
    * The following functions are made up and are not part of TM-Timer.
    */
    if (isBigTick) {
        updateClock(timeLeft)
        showColons() // (04:20)
    }
    else {
        hideColons() // (04 20)
    }
});

Methods

All methods can get called with a timestamp argument. Pass in a current timestamp when you need to sync time with other modules.

• timestamp (ms, number, optional) - The timestamp to be considered as the method's execution time.

.start()

Start counting down.

Calls the first tick (if a tick handler is set with .onTick(fn)).
When called after a .stop() it acts as a "resume" function. There will be no start-tick in this case.

// optional
const timestamp = Date.now()
 
myTimer.start(timestamp)

.getTimeLeft()

Returns how many milliseconds left.

const myTimer = new Timer(3000, callback)
 
myTimer.start()
 
// after 2480 ms (for example)
myTimer.getTimeLeft() // --> 520

.stop()

Stop/Pause counting down.

Run .start() to resume.

const myTimer = new Timer(fiveMinutes, gameOver)
 
myTimer.start()
 
// Take a break
myTimer.stop()
 
// Resume
myTimer.start()

.reset()

Reset the countdown with full original duration.

Can be called whether the timer is running or not. When called while running, it acts like a "restart" and doesn't stop the timer.

const myTimer = new Timer(fiveMinutes, gameOver)
 
myTimer.start()
 
/* after 2 minutes */
myTimer.reset() // re-start counting down five minutes. No stop.

const myTimer = new Timer(fiveMinutes, gameOver)
 
myTimer.start()
 
/* after 2 minutes */
myTimer.stop()
myTimer.reset()
myTimer.start() // start counting down five minutes.

.destroy()

Destroy the timer. Removes duration and bound callbacks.

Cannot be used again unless re-configured.

const myTimer = new Timer(fiveMinutes, gameOver)
 
myTimer.start()
myTimer.destroy()
 
myTimer.set(fiveMinutes)
myTimer.whenDone(gameOver)

Playground

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$ npm run playground