gristlabs_grist-core/app/common/parseDate.ts

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import * as moment from 'moment-timezone';
// When using YY format, use a consistent interpretation in datepicker and in moment parsing: add
// 2000 if the result is at most 10 years greater than the current year; otherwise add 1900. See
// https://bootstrap-datepicker.readthedocs.io/en/latest/options.html#assumenearbyyear and
// "Parsing two digit years" in https://momentjs.com/docs/#/parsing/string-format/.
export const TWO_DIGIT_YEAR_THRESHOLD = 10;
const MAX_TWO_DIGIT_YEAR = new Date().getFullYear() + TWO_DIGIT_YEAR_THRESHOLD - 2000;
// Moment suggests that overriding this is fine, but we need to force TypeScript to allow it.
(moment as any).parseTwoDigitYear = function(yearString: string): number {
const year = parseInt(yearString, 10);
return year + (year > MAX_TWO_DIGIT_YEAR ? 1900 : 2000);
};
// Order of formats to try if the date cannot be parsed as the currently set format.
// Formats are parsed in momentjs strict mode, but separator matching and the MM/DD
// two digit requirement are ignored. Also, partial completion is permitted, so formats
// may match even if only beginning elements are provided.
// TODO: These should be affected by the user's locale/settings.
// TODO: We may want to consider adding default time formats as well to support more
// time formats.
const PARSER_FORMATS: string[] = [
'M D YYYY',
'M D YY',
'M D',
'M',
'MMMM D YYYY',
'MMMM D',
'MMMM Do YYYY',
'MMMM Do',
'MMMM',
'MMM D YYYY',
'MMM D',
'D MMM YYYY',
'D MMM',
'MMM',
'YYYY M D',
'YYYY M',
'YYYY',
'D M YYYY',
'D M YY',
'D M',
'D'
];
interface ParseOptions {
time?: string;
dateFormat?: string;
timeFormat?: string;
timezone?: string;
}
/**
* parseDate - Attempts to parse a date string using several common formats. Returns the
* timestamp of the parsed date in seconds since epoch, or returns null on failure.
* @param {String} date - The date string to parse.
* @param {String} options.dateFormat - The preferred momentjs format to use to parse the
* date. This is attempted before the default formats.
* @param {String} options.time - The time string to parse.
* @param {String} options.timeFormat - The momentjs format to use to parse the time. This
* must be given if options.time is given.
* @param {String} options.timezone - The timezone string for the date/time, which affects
* the resulting timestamp.
*/
export function parseDate(date: string, options: ParseOptions = {}): number | null {
// If no date, return null.
if (!date) {
return null;
}
// Not picky about separators, so replace them in the date and format strings to be spaces.
const separators = /[\W_]+/g;
const dateFormats = PARSER_FORMATS.slice();
// If a preferred parse format is given, set that to be the first parser used.
if (options.dateFormat) {
// Momentjs has an undesirable feature in strict mode where MM and DD
// matches require two digit numbers. Change MM, DD to M, D.
let format = options.dateFormat.replace(/MM+/g, m => (m === 'MM' ? 'M' : m))
.replace(/DD+/g, m => (m === 'DD' ? 'D' : m))
.replace(separators, ' ');
format = _getPartialFormat(date, format);
// Consider some alternatives to the preferred format.
const variations = _buildVariations(format);
dateFormats.unshift(...variations);
}
const cleanDate = date.replace(separators, ' ');
const datetime = (options.time ? `${cleanDate} ${options.time}` : cleanDate).trim();
for (const f of dateFormats) {
// Momentjs has an undesirable feature in strict mode where HH, mm, and ss
// matches require two digit numbers. Change HH, mm, and ss to H, m, and s.
const timeFormat = options.timeFormat ? options.timeFormat.replace(/\bHH\b/g, 'H')
.replace(/\bmm\b/g, 'm')
.replace(/\bss\b/g, 's') : null;
const fullFormat = options.time && timeFormat ? `${f} ${timeFormat}` : f;
const m = moment.tz(datetime, fullFormat, true, options.timezone || 'UTC');
if (m.isValid()) {
return m.valueOf() / 1000;
}
}
return null;
}
// Helper function to get the partial format string based on the input. Momentjs has a feature
// which allows defaulting to the current year, month and/or day if not accounted for in the
// parser. We remove any parts of the parser not given in the input to take advantage of this
// feature.
function _getPartialFormat(input: string, format: string): string {
// Define a regular expression to match contiguous non-separators.
const re = /Y+|M+|D+|[a-zA-Z0-9]+/g;
// Count the number of meaningful parts in the input.
const numInputParts = input.match(re)?.length || 0;
// Count the number of parts in the format string.
let numFormatParts = format.match(re)?.length || 0;
if (numFormatParts > numInputParts) {
// Remove year from format first, to default to current year.
if (/Y+/.test(format)) {
format = format.replace(/Y+/, ' ').trim();
numFormatParts -= 1;
}
if (numFormatParts > numInputParts) {
// Remove month from format next.
format = format.replace(/M+/, ' ').trim();
}
}
return format;
}
// Moment non-strict mode is considered bad, as it's far too lax. But moment's strict mode is too
// strict. We want to allow YY|YYYY for either year specifier, as well as M for MMM or MMMM month
// specifiers. It's silly that we need to create multiple format variations to support this.
function _buildVariations(format: string) {
const variations = new Set<string>([format]);
const otherYear = format.replace(/Y{2,4}/, (m) => (m === 'YY' ? 'YYYY' : (m === 'YYYY' ? 'YY' : m)));
variations.add(otherYear);
variations.add(format.replace(/MMM+/, 'M'));
if (otherYear !== format) {
variations.add(otherYear.replace(/MMM+/, 'M'));
}
return variations;
}