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feat(isDate): add delimiter-less date formats #2659

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01bcb6f
feat: add delimiter-less date formats
xseman Jan 24, 2026
b145c37
docs: update isDate description for formats
xseman Jan 24, 2026
6eafa09
chore: improve coverage
xseman Jan 24, 2026
8f9feb4
chore: implement feedback
xseman Jan 24, 2026
09f0401
chore: improve coverage
xseman Jan 24, 2026
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2 changes: 1 addition & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -102,7 +102,7 @@ Validator | Description
**isCreditCard(str [, options])** | check if the string is a credit card number.<br/><br/> `options` is an optional object that can be supplied with the following key(s): `provider` is an optional key whose value should be a string, and defines the company issuing the credit card. Valid values include `['amex', 'dinersclub', 'discover', 'jcb', 'mastercard', 'unionpay', 'visa']` or blank will check for any provider.
**isCurrency(str [, options])** | check if the string is a valid currency amount.<br/><br/>`options` is an object which defaults to `{ symbol: '$', require_symbol: false, allow_space_after_symbol: false, symbol_after_digits: false, allow_negatives: true, parens_for_negatives: false, negative_sign_before_digits: false, negative_sign_after_digits: false, allow_negative_sign_placeholder: false, thousands_separator: ',', decimal_separator: '.', allow_decimal: true, require_decimal: false, digits_after_decimal: [2], allow_space_after_digits: false }`.<br/>**Note:** The array `digits_after_decimal` is filled with the exact number of digits allowed not a range, for example a range 1 to 3 will be given as [1, 2, 3].
**isDataURI(str)** | check if the string is a [data uri format][Data URI Format].
**isDate(str [, options])** | check if the string is a valid date. e.g. [`2002-07-15`, new Date()].<br/><br/> `options` is an object which can contain the keys `format`, `strictMode` and/or `delimiters`.<br/><br/>`format` is a string and defaults to `YYYY/MM/DD`.<br/><br/>`strictMode` is a boolean and defaults to `false`. If `strictMode` is set to true, the validator will reject strings different from `format`.<br/><br/> `delimiters` is an array of allowed date delimiters and defaults to `['/', '-']`.
**isDate(str [, options])** | check if the string is a valid date. e.g. [`2002-07-15`, `20020715`, new Date()].<br/><br/> `options` is an object which can contain the keys `format`, `strictMode`, `delimiters` and/or `allowDelimiterless`.<br/><br/>`format` is a string and defaults to `YYYY/MM/DD`. Supports delimiter-based formats (e.g., `YYYY/MM/DD`, `DD-MM-YYYY`) and ISO 8601 compliant delimiter-less formats (e.g., `YYYYMMDD`, `YYMMDD`) when `allowDelimiterless` is enabled.<br/><br/>`strictMode` is a boolean and defaults to `false`. If `strictMode` is set to true, the validator will reject strings different from `format`.<br/><br/> `delimiters` is an array of allowed date delimiters and defaults to `['/', '-']`. This option is ignored for delimiter-less formats.<br/><br/>`allowDelimiterless` is a boolean and defaults to `false`. Set to `true` to enable ISO 8601 compliant delimiter-less format validation (e.g., `YYYYMMDD`).
**isDecimal(str [, options])** | check if the string represents a decimal number, such as 0.1, .3, 1.1, 1.00003, 4.0, etc.<br/><br/>`options` is an object which defaults to `{force_decimal: false, decimal_digits: '1,', locale: 'en-US'}`.<br/><br/>`locale` determines the decimal separator and is one of `['ar', 'ar-AE', 'ar-BH', 'ar-DZ', 'ar-EG', 'ar-IQ', 'ar-JO', 'ar-KW', 'ar-LB', 'ar-LY', 'ar-MA', 'ar-QA', 'ar-QM', 'ar-SA', 'ar-SD', 'ar-SY', 'ar-TN', 'ar-YE', 'bg-BG', 'cs-CZ', 'da-DK', 'de-DE', 'el-GR', 'en-AU', 'en-GB', 'en-HK', 'en-IN', 'en-NZ', 'en-US', 'en-ZA', 'en-ZM', 'eo', 'es-ES', 'fa', 'fa-AF', 'fa-IR', 'fr-FR', 'fr-CA', 'hu-HU', 'id-ID', 'it-IT', 'ku-IQ', 'nb-NO', 'nl-NL', 'nn-NO', 'pl-PL', 'pl-Pl', 'pt-BR', 'pt-PT', 'ru-RU', 'sl-SI', 'sr-RS', 'sr-RS@latin', 'sv-SE', 'tr-TR', 'uk-UA', 'vi-VN']`.<br/>**Note:** `decimal_digits` is given as a range like '1,3', a specific value like '3' or min like '1,'.
**isDivisibleBy(str, number)** | check if the string is a number that is divisible by another.
**isEAN(str)** | check if the string is an [EAN (European Article Number)][European Article Number].
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149 changes: 110 additions & 39 deletions src/lib/isDate.js
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Expand Up @@ -4,10 +4,24 @@ const default_date_options = {
format: 'YYYY/MM/DD',
delimiters: ['/', '-'],
strictMode: false,
allowDelimiterless: false,
};

function isValidFormat(format) {
return /(^(y{4}|y{2})[.\/-](m{1,2})[.\/-](d{1,2})$)|(^(m{1,2})[.\/-](d{1,2})[.\/-]((y{4}|y{2})$))|(^(d{1,2})[.\/-](m{1,2})[.\/-]((y{4}|y{2})$))/gi.test(format);
function isValidFormat(format, allowDelimiterless) {
// Formats with delimiters
const withDelimiters = /(^(y{4}|y{2})[\.\/-](m{1,2})[\.\/-](d{1,2})$)|(^(m{1,2})[\.\/-](d{1,2})[\.\/-]((y{4}|y{2})$))|(^(d{1,2})[\.\/-](m{1,2})[\.\/-]((y{4}|y{2})$))/gi;

if (withDelimiters.test(format)) {
return true;
}

// Formats without delimiters (e.g., YYYYMMDD, YYMMDD)
if (allowDelimiterless) {
const withoutDelimiters = /^(y{4}|y{2})(m{2})(d{2})$/gi;
return withoutDelimiters.test(format);
}

return false;
}

function zip(date, format) {
Expand All @@ -21,14 +35,85 @@ function zip(date, format) {
return zippedArr;
}

function hasNoDelimiter(format, delimiters) {
return !delimiters.some(delimiter => format.indexOf(delimiter) !== -1);
}

function parseDelimiterlessFormat(format) {
// Extract component positions from format like
// YYYYMMDD, YYMMDD (ISO 8601 compliant)
const lowerFormat = format.toLowerCase();
const components = [];
let pos = 0;

while (pos < lowerFormat.length) {
const char = lowerFormat[pos];
let len = 0;

while (pos + len < lowerFormat.length && lowerFormat[pos + len] === char) {
len += 1;
}

components.push({
type: char,
start: pos,
length: len,
});

pos += len;
}

return components;
}

function extractDatePartsWithoutDelimiter(input, format) {
const components = parseDelimiterlessFormat(format);
const dateObj = {};

for (const comp of components) {
dateObj[comp.type] = input.substring(
comp.start,
comp.start + comp.length
);
}

return dateObj;
}

export default function isDate(input, options) {
if (typeof options === 'string') { // Allow backward compatibility for old format isDate(input [, format])
// Allow backward compatibility for old format isDate(input [, format])
if (typeof options === 'string') {
options = merge({ format: options }, default_date_options);
} else {
options = merge(options, default_date_options);
}
if (typeof input === 'string' && isValidFormat(options.format)) {
if (options.strictMode && input.length !== options.format.length) return false;

// Handle non-string input
if (typeof input !== 'string' || !isValidFormat(options.format, options.allowDelimiterless)) {
if (!options.strictMode) {
return (
Object.prototype.toString.call(input) === '[object Date]' &&
isFinite(input)
);
}
return false;
}

if (options.strictMode && input.length !== options.format.length) {
return false;
}

let dateObj;

// Check if format has no delimiters (e.g., YYYYMMDD)
if (hasNoDelimiter(options.format, options.delimiters)) {
// Delimiter-less format parsing
if (input.length !== options.format.length) {
return false;
}
dateObj = extractDatePartsWithoutDelimiter(input, options.format);
} else {
// Original delimiter-based parsing
const formatDelimiter = options.delimiters
.find(delimiter => options.format.indexOf(delimiter) !== -1);
const dateDelimiter = options.strictMode
Expand All @@ -38,7 +123,7 @@ export default function isDate(input, options) {
input.split(dateDelimiter),
options.format.toLowerCase().split(formatDelimiter)
);
const dateObj = {};
dateObj = {};

for (const [dateWord, formatWord] of dateAndFormat) {
if (!dateWord || !formatWord || dateWord.length !== formatWord.length) {
Expand All @@ -47,48 +132,34 @@ export default function isDate(input, options) {

dateObj[formatWord.charAt(0)] = dateWord;
}
}

let fullYear = dateObj.y;

// Check if the year starts with a hyphen
if (fullYear.startsWith('-')) {
return false; // Hyphen before year is not allowed
}

if (dateObj.y.length === 2) {
const parsedYear = parseInt(dateObj.y, 10);

if (isNaN(parsedYear)) {
return false;
}

const currentYearLastTwoDigits = new Date().getFullYear() % 100;
let fullYear = dateObj.y;

if (parsedYear < currentYearLastTwoDigits) {
fullYear = `20${dateObj.y}`;
} else {
fullYear = `19${dateObj.y}`;
}
}
// Check if the year starts with a hyphen
if (fullYear.startsWith('-')) {
return false; // Hyphen before year is not allowed
}

let month = dateObj.m;
if (dateObj.y.length === 2) {
const parsedYear = parseInt(dateObj.y, 10);

if (dateObj.m.length === 1) {
month = `0${dateObj.m}`;
if (isNaN(parsedYear)) {
return false;
}

let day = dateObj.d;
const currentYearLastTwoDigits = new Date().getFullYear() % 100;

if (dateObj.d.length === 1) {
day = `0${dateObj.d}`;
if (parsedYear < currentYearLastTwoDigits) {
fullYear = `20${dateObj.y}`;
} else {
fullYear = `19${dateObj.y}`;
}

return new Date(`${fullYear}-${month}-${day}T00:00:00.000Z`).getUTCDate() === +dateObj.d;
}

if (!options.strictMode) {
return Object.prototype.toString.call(input) === '[object Date]' && isFinite(input);
}
const month = dateObj.m.length === 1 ? `0${dateObj.m}` : dateObj.m;
const day = dateObj.d.length === 1 ? `0${dateObj.d}` : dateObj.d;

return false;
const dateString = `${fullYear}-${month}-${day}T00:00:00.000Z`;
return new Date(dateString).getUTCDate() === +dateObj.d;
}
58 changes: 58 additions & 0 deletions test/validators.test.js
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Expand Up @@ -14467,6 +14467,64 @@ describe('Validators', () => {
'abc.04.05.2024',
],
});
// Test delimiter-less format YYYYMMDD
test({
validator: 'isDate',
args: [{ format: 'YYYYMMDD', allowDelimiterless: true }],
valid: [
'20200229', // leap year
'20200115',
'20140215',
'20140315',
'19991231',
'20000101',
],
invalid: [
'2020-02-29',
'2020/02/29',
'20200230', // invalid date
'20190229', // non-leap year
'20200431', // invalid date
'2020229', // too short
'202002290', // too long
'',
'abcdefgh',
'2020ab29',
'-20200229',
],
});
// Test delimiter-less format YYMMDD (two-digit year)
test({
validator: 'isDate',
args: [{ format: 'YYMMDD', allowDelimiterless: true }],
valid: [
'200229', // 2020 leap year
'140215',
'991231',
'000101',
],
invalid: [
'20200229',
'2020-02-29',
'20229', // too short
'2002290', // too long
'',
'abcdef',
'20ab29',
'-200229',
],
});
// Test that delimiter-less formats are rejected without allowDelimiterless option
test({
validator: 'isDate',
args: [{ format: 'YYYYMMDD' }],
valid: [],
invalid: [
'20200229',
'20020715',
'19991231',
],
});
// emulating Pacific time zone offset & time
// which could potentially result in UTC conversion issues
timezone_mock.register('US/Pacific');
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