Walltime-js is a JavaScript library for easily translating a UTC time to a "Wall Time" for a particular time zone.
Dates in JavaScript do not properly account for daylight savings time for regions other than your own browser configured time zone.
For example:
- Your API sends UTC times in JSON but you need to display them for Chicago time zone to a user viewing your page in Los Angeles.
- What was the local time in Chicago when the first humans landed on the Moon?
Here is an example unit test showing how to use the WallTime API to get the local time in Chicago for the Moon landing.
<script src="/path/to/walltime-data.js"></script>
<script src="/path/to/walltime.js"></script>
<script type="text/javascript">
it("can convert first moon landing time", function () {
// Apollo 11 was the spaceflight that landed the first humans on the Moon,
// Americans Neil Armstrong and Buzz Aldrin, on July 20, 1969, at 20:18 UTC.
var landingTime = Date.UTC(1969, 6, 20, 20, 18, 0, 0),
chicagoLandingTime = WallTime.UTCToWallTime(landingTime, "America/Chicago");
chicagoLandingTime.getFullYear().should.equal(1969);
chicagoLandingTime.getMonth().should.equal(6);
chicagoLandingTime.getDate().should.equal(20);
chicagoLandingTime.getHours().should.equal(15);
chicagoLandingTime.getMinutes().should.equal(18);
});
</script><script type="text/javascript" src="require.js"></script>
<script type="text/javascript" src="path/to/walltime-data.js"></script>
<script type="text/javascript">
require.config({
paths: {
walltime: 'path/to/walltime'
}
});
define(['walltime'], function(WallTime){
var someUTCDate = new Date(),
chicagoWallTime = WallTime.UTCToWallTime(someUTCDate, "America/Chicago");
});
</script>To limit the size of WallTime.js, you should only use the data for the time zone files you need.
By default, walltime-data.js contains northamerica, europe and australasia, which encompass most of the world, but is 479k (minified). By narrowing it down to just northamerica, you could save 300k. Adding gzip compression could get you down as low as 16k.
To get the latest Olson files
git submodule init && git submodule update
To build all the data for all the time zone files
grunt data
To build data for northamerica only
grunt data --filename=northamerica
To build data for northamerica and europe
grunt data --filename=northamerica,europe
To build data for America/Chicago only
grunt data --filename=northamerica --zonename=America/Chicago
To build individual data files for each time zone
grunt individual
# Optionally, pass a format parameter for naming
grunt individual --format "walltime-data_%s" # Becomes `walltime-data_America-Chicago.min.js`
By default the files are saved to ./client/walltime.js etc.
This project uses Node.js and Grunt.
To get setup
# Clone the repo
git clone https://github.com/sproutsocial/walltime-js.git && cd walltime-js
# Install the dependencies
npm install
To run tests and lint source code
grunt test
To make new tests, create a new spec coffee file in the test directory.
Copyright (c) 2013 Sprout Social, Inc.
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:
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