Chrono
A natural language date parser in Javascript, designed for extracting date information from any given text. (Java version is also available here)
Chrono supports most date and time formats, such as :
- Today, Tomorrow, Yesterday, Last Friday, etc
- 17 August 2013 - 19 August 2013
- This Friday from 13:00 - 16.00
- 5 days ago
- Sat Aug 17 2013 18:40:39 GMT+0900 (JST)
- 2014-11-30T08:15:30-05:30
Install
npm (recommended)
Just run:
$ npm i --save chrono-node
And start using chrono:
var chrono = require('chrono-node')
chrono.parseDate('An appointment on Sep 12-13')
Bower
Prefer bower? You can do that, too:
Just run:
$ bower install chrono
And use:
<script src="bower_components/chrono/chrono.min.js"></script>
<script>chrono.parseDate('An appointment on Sep 12-13')</script>
Other Options:
Doing something else? No worries. Try these:
Platform | Installation |
---|
CDN | Via jsDelivr: <script src="https://cdn.jsdelivr.net/chrono/VERSION/chrono.min.js"></script> |
Rails | Install from Rails Assets by adding this to your Gemfile: gem 'rails-assets-chrono', source: 'https://rails-assets.org' |
Swift | Try using the community-made chrono-swift wrapper. |
Browserify
Chrono's modules are linked and packaged using Browserify on src/chrono.js
. By default, chrono.js
file exports chrono
object as a window global.
browserify src/chrono.js --s chrono -o chrono.js
Usage
Simply pass a string to function chrono.parseDate
or chrono.parse
.
> var chrono = require('chrono-node')
> chrono.parseDate('An appointment on Sep 12-13')
Fri Sep 12 2014 12:00:00 GMT-0500 (CDT)
> chrono.parse('An appointment on Sep 12-13');
[ { index: 18,
text: 'Sep 12-13',
tags: { ENMonthNameMiddleEndianParser: true },
start:
{ knownValues: [Object],
impliedValues: [Object] },
end:
{ knownValues: [Object],
impliedValues: [Object] } } ]
Reference Date
Today's "Friday" is different from last month's "Friday".
The meaning of the referenced dates depends on when they are mentioned.
Chrono lets you define a reference date using chrono.parse(text, ref)
and chrono.parseDate(text, ref)
.
> chrono.parseDate('Friday', new Date(2012,7,23));
Fri Aug 24 2012 12:00:00 GMT+0700 (ICT)
> chrono.parseDate('Friday', new Date(2012,7,1));
Fri Aug 03 2012 12:00:00 GMT+0700 (ICT)
Detailed Parsed Results
The function chrono.parse
returns detailed parsing results as objects of class chrono.ParsedResult
.
var results = chrono.parse('I have an appointment tomorrow from 10 to 11 AM')
results[0].index
results[0].text
results[0].ref
results[0].start.date()
results[0].end.date()
ParsedResult
start
The parsed date components as a ParsedComponents objectend
Similar to start
but can be null.index
The location within the input text of this resulttext
The text this result that appears in the inputref
The reference date of this result
ParsedComponents
A group of found date and time components (year, month, hour, etc). ParsedComponents objects consist of knownValues
and impliedValues
.
assign(component, value)
Set known value to the componentimply(component, value)
Set implied value to the componentget(component)
Get known or implied value for the componentisCertain(component)
return true if the value of the component is known.date()
Create a javascript Date
> var results = new chrono.parse('2016-03-08T01:16:07+02:00');
> results[0].start.assign('timezoneOffset', 0);
> var d = results[0].start.date();
> d.toString();
'Tue Mar 08 2016 01:16:07 GMT+0000 (GMT)'
Strict vs Casual
Chrono comes with strict
mode that parse only formal date patterns.
chrono.strict.parseDate('Today');
chrono.strict.parseDate('Friday');
chrono.strict.parseDate('2016-07-01');
chrono.strict.parseDate('Jul 01 2016');
chrono.parseDate('Today');
chrono.casual.parseDate('Friday');
chrono.casual.parseDate('Jul 01 2016');
chrono.casual.parseDate('Friday');
Customize Chrono
Chrono’s extraction pipeline are mainly separated into 'parse' and ‘refine’ phases. During parsing, ‘parsers’ (Parser
) are used to extract patterns from the input text. The parsed results (ParsedResult) are the combined, sorted, then refine using ‘refiners’ (Refiner
). In the refining phase, the results can be combined, filtered-out, or attached with additional information.
Parser
Parser is a module for low-level pattern-based parsing. Ideally, each parser should be designed to handle a single specific date format. User can add new type of parsers for supporting new date formats or languages.
var christmasParser = new chrono.Parser();
christmasParser.pattern = function () { return /Christmas/i }
christmasParser.extract = function(text, ref, match, opt) {
return new chrono.ParsedResult({
ref: ref,
text: match[0],
index: match.index,
start: {
day: 25,
month: 12,
}
});
}
var custom = new chrono.Chrono();
custom.parsers.push(christmasParser);
custom.parseDate("I'll arrive at 2.30AM on Christmas night")
To create a custom parser, override pattern
and extract
methods on an object of class chrono.Parser
.
- The
pattern
method must return RegExp
object of searching pattern. - The
extract
method will be called with the
match object when the pattern is found. This function must create and return a result (or null to skip).
Refiner
Refiner is a heigher level module for improving or manipurating the results. User can add a new type of refiner to customize Chrono's results or to add some custom logic to Chrono.
var guessPMRefiner = new chrono.Refiner();
guessPMRefiner.refine = function(text, results, opt) {
results.forEach(function (result) {
if (!result.start.isCertain('meridiem')
&& result.start.get('hour') >= 1 && result.start.get('hour') < 4) {
result.start.assign('meridiem', 1);
result.start.assign('hour', result.start.get('hour') + 12);
}
});
return results;
}
var custom = new chrono.Chrono();
custom.refiners.push(guessPMRefiner);
custom.parseDate("This is at 2.30");
custom.parseDate("This is at 2.30 AM");
In the example, a custom refiner is created for assigning PM to parsing results with ambiguous meridiem. The refine
method of the refiner class will be called with parsing results (from parsers or other previous refiners). The method must return an array of the new results (which, in this case, we modified those results in place).
Development Guides
This guide explains how to setup chrono project for prospective contributors.
git clone https://github.com/wanasit/chrono.git chrono
cd chrono
npm install
npm run test
Chrono's source files is in src
directory. The built bundle (chrono.js
and chrono.min.js
) can be built by Browserify on src/chrono.js
using the following command
npm run make
Parsing date from text is complicated. Sometimes, a small change can have effects on unexpected places. So, Chrono is a heavily tested library. Commits that break a test shouldn't be allowed in any condition.
Chrono's unit testing is based-on Qunit and Karma. During the developement, I recommend running Karma test together with watchify.
# Start karma
npm run karma
# Start watch (run on a different terminal)
npm run watch