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Last active March 27, 2024 20:59
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Stopwatch in javascript
Copyright (c) 2010-2015 Giulia Alfonsi <electric.g@gmail.com>
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Stopwatch</title>
</head>
<body onload="show();">
<div>Time: <span id="time"></span></div>
<input type="button" value="start" onclick="start();">
<input type="button" value="stop" onclick="stop();">
<input type="button" value="reset" onclick="reset()">
</body>
</html>
// Simple example of using private variables
//
// To start the stopwatch:
// obj.start();
//
// To get the duration in milliseconds without pausing / resuming:
// var x = obj.time();
//
// To pause the stopwatch:
// var x = obj.stop(); // Result is duration in milliseconds
//
// To resume a paused stopwatch
// var x = obj.start(); // Result is duration in milliseconds
//
// To reset a paused stopwatch
// obj.stop();
//
var clsStopwatch = function() {
// Private vars
var startAt = 0; // Time of last start / resume. (0 if not running)
var lapTime = 0; // Time on the clock when last stopped in milliseconds
var now = function() {
return (new Date()).getTime();
};
// Public methods
// Start or resume
this.start = function() {
startAt = startAt ? startAt : now();
};
// Stop or pause
this.stop = function() {
// If running, update elapsed time otherwise keep it
lapTime = startAt ? lapTime + now() - startAt : lapTime;
startAt = 0; // Paused
};
// Reset
this.reset = function() {
lapTime = startAt = 0;
};
// Duration
this.time = function() {
return lapTime + (startAt ? now() - startAt : 0);
};
};
var x = new clsStopwatch();
var $time;
var clocktimer;
function pad(num, size) {
var s = "0000" + num;
return s.substr(s.length - size);
}
function formatTime(time) {
var h = m = s = ms = 0;
var newTime = '';
h = Math.floor( time / (60 * 60 * 1000) );
time = time % (60 * 60 * 1000);
m = Math.floor( time / (60 * 1000) );
time = time % (60 * 1000);
s = Math.floor( time / 1000 );
ms = time % 1000;
newTime = pad(h, 2) + ':' + pad(m, 2) + ':' + pad(s, 2) + ':' + pad(ms, 3);
return newTime;
}
function show() {
$time = document.getElementById('time');
update();
}
function update() {
$time.innerHTML = formatTime(x.time());
}
function start() {
clocktimer = setInterval("update()", 1);
x.start();
}
function stop() {
x.stop();
clearInterval(clocktimer);
}
function reset() {
stop();
x.reset();
update();
}
@poa00
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poa00 commented Mar 27, 2024

I would change https://gist.github.com/electricg/4372563#file-stopwatch-js-L61

var h = m = s = ms = 0;

to

var h, m, s, ms = 0;

@rstormsf but that leaves all variables except ms to be of type undefined, which makes them ambiguous. At least setting them all to 0 gives them all the number type.

@NormanBenbrahim After reading the comments, I'm curious whether one way or the other is the (more) correct way to go about writing this... sweet gist though!

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