chrono-node

You can manipulate or improve parsing results by adding a Refiner to the refiners array. Refiners operate at a higher level than parsers; they receive the combined results from all parsers (and previous refiners) and can filter, merge, or modify them.

A refiner must implement:

• refine(context, results): A function that accepts the ParsingContext and an array of ParsingResult[], and returns a modified or new array of ParsingResult[].

Note: You can modify the results in place or return a new array.

const custom = chrono.casual.clone();
custom.refiners.push({
    refine: (context, results) => {
        // If there is no AM/PM (meridiem) specified,
        // let all time between 1:00 - 4:00 be PM (13.00 - 16.00)
        results.forEach((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;
    }
});

// This will be parsed as PM.
// > Tue Dec 16 2014 14:30:00 GMT-0600 (CST) 
custom.parseDate("This is at 2.30");

// Unless the 'AM' part is specified
// > Tue Dec 16 2014 02:30:00 GMT-0600 (CST)
custom.parseDate("This is at 2.30 AM");

You can extend Chrono's parsing capabilities by adding a new Parser to the parsers array. A parser is a low-level module designed to handle specific date formats using a regular expression.

To implement a parser, you must provide:

1. pattern(): A function that returns a RegExp used to identify the date pattern in the input text.
2. extract(): A function that takes the ParsingContext and the RegExpMatchArray to return ParsingComponents, a ParsingResult, or a mapping of components to values.

It is recommended to use chrono.casual.clone() or chrono.strict.clone() to avoid mutating the original instances.

const custom = chrono.casual.clone();
custom.parsers.push({
    pattern: () => { return /\bChristmas\b/i },
    extract: (context, match) => {
        return {
            day: 25, month: 12
        }
    }
});

custom.parseDate("I'll arrive at 2.30AM on Christmas night");
// Wed Dec 25 2013 02:30:00 GMT+0900 (JST)
// 'at 2.30AM on Christmas'

The chrono.parse method returns ParsedResult objects. Each result contains:

• refDate: Date: The reference date used for this result.
• index: number: The start index of the matched text.
• text: string: The original text fragment.
• start: ParsedComponents: The start date components.
• end?: ParsedComponents: The end date components (if applicable).
• date: () => Date: A function to create a Javascript Date from the result.

ParsedComponents allows you to inspect specific parts of the date:

• get(component: Component): number | null: Returns the value for a component (e.g., 'day', 'month', 'hour').
• isCertain(component: Component): boolean: Checks if the component value is known or implied.
• date(): Date: Returns the full Javascript Date object.

const results = chrono.parse('I have an appointment tomorrow from 10 to 11 AM');

results[0].start.get('day');    // 14
results[0].start.get('month');  // 12
results[0].start.get('hour');   // 10 
results[0].start.date();        // Sun Dec 14 2014 10:00:00 ...