Function parseDate

src/util/number.ts:502–561

(value: unknown)

 * @return date Never be null/undefined. If invalid, return `new Date(NaN)`.
 */
export function parseDate(value: unknown): Date {
    if (value instanceof Date) {
        return value;
    }
    else if (zrUtil.isString(value)) {
        // Different browsers parse date in different way, so we parse it manually.
        // Some other issues:
        // new Date('1970-01-01') is UTC,
        // new Date('1970/01/01') and new Date('1970-1-01') is local.
        // See issue #3623
        const match = TIME_REG.exec(value);

        if (!match) {
            // return Invalid Date.
            return new Date(NaN);
        }

        // Use local time when no timezone offset is specified.
        if (!match[8]) {
            // match[n] can only be string or undefined.
            // But take care of '12' + 1 => '121'.
            return new Date(
                +match[1],
                +(match[2] || 1) - 1,
                +match[3] || 1,
                +match[4] || 0,
                +(match[5] || 0),
                +match[6] || 0,
                match[7] ? +match[7].substring(0, 3) : 0
            );
        }
        // Timezoneoffset of Javascript Date has considered DST (Daylight Saving Time,
        // https://tc39.github.io/ecma262/#sec-daylight-saving-time-adjustment).
        // For example, system timezone is set as "Time Zone: America/Toronto",
        // then these code will get different result:
        // `new Date(1478411999999).getTimezoneOffset();  // get 240`
        // `new Date(1478412000000).getTimezoneOffset();  // get 300`
        // So we should not use `new Date`, but use `Date.UTC`.
        else {
            let hour = +match[4] || 0;
            if (match[8].toUpperCase() !== 'Z') {
                hour -= +match[8].slice(0, 3);
            }
            return new Date(Date.UTC(
                +match[1],
                +(match[2] || 1) - 1,
                +match[3] || 1,
                hour,
                +(match[5] || 0),
                +match[6] || 0,
                match[7] ? +match[7].substring(0, 3) : 0
            ));
        }
    }
    else if (value == null) {
        return new Date(NaN);
    }