locutus
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Locutus other languages' standard libraries to JavaScript for fun and educational purposes
210 lines (209 loc) • 7 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.Parse = Parse;
const GO_PARSE_TOKENS = [
'Z07:00',
'-07:00',
'-0700',
'2006',
'PM',
'pm',
'15',
'06',
'01',
'02',
'03',
'04',
'05',
'1',
'2',
'3',
];
const escapeRegex = (value) => value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
const isTokenAt = (layout, index) => GO_PARSE_TOKENS.find((token) => layout.startsWith(token, index));
const tokenRegex = (token) => {
switch (token) {
case '2006':
return '(\\d{4})';
case '06':
return '(\\d{2})';
case '01':
return '(0[1-9]|1[0-2])';
case '1':
return '([1-9]|1[0-2])';
case '02':
return '(0[1-9]|[12]\\d|3[01])';
case '2':
return '([1-9]|[12]\\d|3[01])';
case '15':
return '([01]\\d|2[0-3])';
case '03':
return '(0[1-9]|1[0-2])';
case '3':
return '([1-9]|1[0-2])';
case '04':
return '([0-5]\\d)';
case '05':
return '([0-5]\\d)';
case 'PM':
return '(AM|PM)';
case 'pm':
return '(am|pm)';
case '-0700':
return '([+-]\\d{4})';
case '-07:00':
return '([+-]\\d{2}:\\d{2})';
case 'Z07:00':
return '(Z|[+-]\\d{2}:\\d{2})';
default:
return escapeRegex(token);
}
};
const parseOffsetMinutes = (offset) => {
if (offset === 'Z') {
return 0;
}
const compact = offset.match(/^([+-])(\d{2})(\d{2})$/);
if (compact?.[1] && compact[2] && compact[3]) {
const sign = compact[1] === '-' ? -1 : 1;
const hours = Number.parseInt(compact[2], 10);
const minutes = Number.parseInt(compact[3], 10);
return sign * (hours * 60 + minutes);
}
const colon = offset.match(/^([+-])(\d{2}):(\d{2})$/);
if (colon?.[1] && colon[2] && colon[3]) {
const sign = colon[1] === '-' ? -1 : 1;
const hours = Number.parseInt(colon[2], 10);
const minutes = Number.parseInt(colon[3], 10);
return sign * (hours * 60 + minutes);
}
throw new TypeError('Parse(): invalid offset');
};
const resolveTwoDigitYear = (year) => (year >= 69 ? 1900 + year : 2000 + year);
function Parse(layout, value) {
// discuss at: https://locutus.io/golang/time/Parse
// parity verified: Go 1.23
// original by: Kevin van Zonneveld (https://kvz.io)
// note 1: Supports a focused subset of Go layout tokens and parses into a JavaScript Date.
// note 1: Layout markers outside the supported subset are treated as literals.
// note 2: Returned Date is absolute time in UTC; timezone offsets in input are respected.
// example 1: Parse('2006-01-02', '2026-03-03')
// returns 1: new Date('2026-03-03T00:00:00.000Z')
// example 2: Parse('2006-01-02 15:04:05', '2026-03-03 13:14:15')
// returns 2: new Date('2026-03-03T13:14:15.000Z')
// example 3: Parse('01/02/06 03:04 PM', '03/03/26 01:14 PM')
// returns 3: new Date('2026-03-03T13:14:00.000Z')
// example 4: Parse('2006-01-02T15:04:05-07:00', '2026-03-03T13:14:15+02:30')
// returns 4: new Date('2026-03-03T10:44:15.000Z')
// example 5: Parse('2006-01-02T15:04:05Z07:00', '2026-03-03T13:14:15Z')
// returns 5: new Date('2026-03-03T13:14:15.000Z')
const resolvedLayout = String(layout);
const resolvedValue = String(value);
const tokenOrder = [];
let regexSource = '^';
for (let i = 0; i < resolvedLayout.length;) {
const token = isTokenAt(resolvedLayout, i);
if (token) {
regexSource += tokenRegex(token);
tokenOrder.push(token);
i += token.length;
continue;
}
const char = resolvedLayout[i];
if (char === undefined) {
break;
}
regexSource += escapeRegex(char);
i += 1;
}
regexSource += '$';
const match = new RegExp(regexSource).exec(resolvedValue);
if (!match) {
throw new TypeError('Parse(): input does not match layout');
}
let year = 1970;
let month = 1;
let day = 1;
let hour24 = 0;
let minute = 0;
let second = 0;
let hour12;
let ampm;
let offsetMinutes = 0;
let hasOffset = false;
let matchIndex = 1;
for (const token of tokenOrder) {
const raw = match[matchIndex];
matchIndex += 1;
if (!raw) {
continue;
}
switch (token) {
case '2006':
year = Number.parseInt(raw, 10);
break;
case '06':
year = resolveTwoDigitYear(Number.parseInt(raw, 10));
break;
case '01':
case '1':
month = Number.parseInt(raw, 10);
break;
case '02':
case '2':
day = Number.parseInt(raw, 10);
break;
case '15':
hour24 = Number.parseInt(raw, 10);
break;
case '03':
case '3':
hour12 = Number.parseInt(raw, 10);
break;
case '04':
minute = Number.parseInt(raw, 10);
break;
case '05':
second = Number.parseInt(raw, 10);
break;
case 'PM':
case 'pm':
ampm = raw.toUpperCase() === 'PM' ? 'PM' : 'AM';
break;
case '-0700':
case '-07:00':
case 'Z07:00':
offsetMinutes = parseOffsetMinutes(raw);
hasOffset = true;
break;
default:
break;
}
}
if (hour12 !== undefined) {
if (ampm === 'PM' && hour12 < 12) {
hour24 = hour12 + 12;
}
else if (ampm === 'AM' && hour12 === 12) {
hour24 = 0;
}
else {
hour24 = hour12;
}
}
if (month < 1 || month > 12 || day < 1 || day > 31 || hour24 < 0 || hour24 > 23 || minute < 0 || minute > 59) {
throw new TypeError('Parse(): invalid datetime components');
}
const localMillis = Date.UTC(year, month - 1, day, hour24, minute, second);
const localCheck = new Date(localMillis);
if (localCheck.getUTCFullYear() !== year ||
localCheck.getUTCMonth() + 1 !== month ||
localCheck.getUTCDate() !== day ||
localCheck.getUTCHours() !== hour24 ||
localCheck.getUTCMinutes() !== minute ||
localCheck.getUTCSeconds() !== second) {
throw new TypeError('Parse(): invalid datetime components');
}
const utcMillis = hasOffset ? localMillis - offsetMinutes * 60_000 : localMillis;
return new Date(utcMillis);
}