jackwener/OpenCLI · error · ArgumentError

--depart must be before --return (got ${depart} .. ${ret})

Error message

--depart must be before --return (got ${depart} .. ${ret})

What it means

ArgumentError thrown when the parsed --depart date is not strictly before the parsed --return date (including equal dates and inverted ranges). A round trip requires depart < return, so the library validates this before building the search URL.

Source

Thrown at clis/trip/flight-round.js:54

    columns: [
        'rank',
        'airline',
        'departureTime', 'departureAirport',
        'arrivalTime', 'arrivalAirport',
        'duration', 'stops',
        'price', 'currency',
        'url',
    ],
    func: async (page, kwargs) => {
        const fromCode = parseIataCode('from', kwargs.from);
        const toCode = parseIataCode('to', kwargs.to);
        if (fromCode === toCode) {
            throw new ArgumentError(`--from and --to must differ (got ${fromCode})`);
        }
        const depart = parseIsoDate('depart', kwargs.depart);
        const ret = parseIsoDate('return', kwargs.return);
        if (depart >= ret) {
            throw new ArgumentError(`--depart must be before --return (got ${depart} .. ${ret})`);
        }
        const limit = parseListLimit(kwargs.limit);

        const searchUrl = buildFlightRoundSearchUrl(fromCode, toCode, depart, ret);
        await page.goto(searchUrl);
        const waitResult = await page.evaluate(WAIT_FOR_FLIGHTS_JS);
        if (waitResult === 'captcha') {
            throw new AuthRequiredError('trip.com', 'Trip.com is asking for a verification; complete it in your browser session and retry');
        }
        if (waitResult !== 'content') {
            throw new CommandExecutionError(`Trip.com flight page did not render flight cards (state=${String(waitResult)})`);
        }
        const raw = await page.evaluate(buildFlightExtractJs());
        if (!Array.isArray(raw)) {
            const reason = raw && typeof raw === 'object' && typeof raw.error === 'string'
                && /^malformed flight card \d+: [a-z /]+$/.test(raw.error)
                ? `: ${raw.error}`
                : '';

View on GitHub (pinned to 49907e53dc)

Solutions

  1. Ensure --return is a strictly later date than --depart (use YYYY-MM-DD ISO format)
  2. Check the order of variables feeding these flags in your script
  3. Verify date formats match the expected ISO date (parseIsoDate input)
  4. For same-day travel, check whether the site/command supports it or pick different dates

Example fix

// before
--depart 2026-09-08 --return 2026-09-01
// after
--depart 2026-09-01 --return 2026-09-08
Defensive patterns

Strategy: validation

Validate before calling

function validDateRange(depart, ret) {
    const d = new Date(depart), r = new Date(ret);
    return !isNaN(d.getTime()) && !isNaN(r.getTime()) && d.getTime() < r.getTime();
}
if (!validDateRange(depart, ret)) throw new Error('--depart must be an earlier ISO date than --return');

Type guard

function isOrderedDatePair(a, b): boolean {
    return Date.parse(a) < Date.parse(b);
}

Try / catch

try {
    await runFlightRound({ from, to, depart, ret });
} catch (e) {
    if (e instanceof ArgumentError && /--depart must be before --return/.test(e.message)) {
        console.error(`Bad date range: ${e.message}. Use YYYY-MM-DD with return > depart.`);
    } else { throw e; }
}

Prevention

When it happens

Trigger: Calling flight-round with --depart equal to --return (same-day), or with the dates swapped so depart > return, e.g. --depart 2026-09-08 --return 2026-09-01.

Common situations: DD/MM vs MM/DD confusion producing an inverted range; passing ISO strings in the wrong order via variables; users wanting same-day trips unsupported by this command; timezone-insensitive date parsing surprises.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/be5e784eede8996a. Report an issue: GitHub.