isWeekend — GTM Variable Template for Date

VARIABLES › DATE

isWeekend EXTENDED Date

Direct (.tpl) Apply (.tpl) Add to GTM

Determines if a given date string is a weekend (Saturday or Sunday) and returns true or false.

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When to Use This

Conditional Logic

Branch logic based on conditions — if/else, ternary, boolean gates.

Date & Time

Calculate durations, differences, and time-based operations on date values.

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Examples

Saturday▶ Try

INPUT

Target Date: 2024-04-27

OUTPUT

true

Wednesday▶ Try

INPUT

Target Date: 2024-04-24

OUTPUT

false

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Live Sandbox

This is what you'll see when you open this variable in Google Tag Manager. Hover the icons for details.

isWeekend

Read-Only Try Live

Target Date

💾 The target date in YYYY-MM-DD format.

Supported formats:
  ✓ String

Input Setup

Input Function (optional)

⚙️ Optional pre-processing function applied to the input before internal logic (e.g., convert object to string, normalize case). Internal transformations such as case handling will still apply afterward.

Result Handling

Output Function (optional)

⚙️ Optional function to apply to the result before returning it (e.g., str => str + ' €', val => val !== undefined for boolean conversion). Useful for chaining transformations on the output.

Target Date string

💡 Type any text to see the result update live

🎯 Using special value — click input to type instead

Test with:

Falsy undefined null "" empty 0 false NaN

Truthy true 42 "hello" {} empty [] empty {a:1} [1,2,3]

🔗 Result Handling — Chain Variables

Chain apply-mode variables to the output. Each variable receives the result of the previous one.

isWeekend()

+ Chain another variable

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Related Variables

Same category: Date

→ addDays → basicDateToExtended → calculateDaysDifference → calculateLeadTime → currentTimestamp → dateToUnixTimestamp → daysToMilliseconds → extendedDateToBasic → getDayIndexFromDateString → getDayName → getDayNameFromDateString → getDayNameShort → getHourOfDay → getMonthName → getMonthNameShort → hoursToMilliseconds → isBusinessHours → millisecondsToDays → millisecondsToHours → millisecondsToMinutes → millisecondsToSeconds → minutesToMilliseconds → reverseDateCompactDay1st → reverseDateCompactYear1st → reverseDateSlash → secondsToMilliseconds → subtractDays → timestampToDayIndex → unixTimestampToDate

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Under the Hood

📜 View Implementation Code

/**
* Checks if a given date string is a weekend.
*
* @param {string} data.src - Target date in YYYY-MM-DD format.
* @param {Function|string} [data.out] - Optional output handler.
*
* Direct-mode specific parameters:
* @param {Function} [data.pre] - Optional pre-processor function to transform src.
*
* @returns {boolean|undefined} True if Saturday or Sunday, false if weekday. Undefined if invalid.
*
* @framework ggLowCodeGTMKit
*/
const makeNumber = require('makeNumber');

const isWeekend = function(dateString) {
    if (typeof dateString !== 'string') return undefined;

    const reDateFormatISO8601 = "^(\\d{4})-(\\d{2})-(\\d{2})$";
    const matchParts = dateString.match(reDateFormatISO8601);
    if (matchParts === null) return undefined;

    let year = makeNumber(matchParts[1]);
    let month = makeNumber(matchParts[2]);
    let day = makeNumber(matchParts[3]);

    function isLeapYear(y) {
        return (y % 4 === 0 && y % 100 !== 0) || (y % 400 === 0);
    }

    function dateToAbsoluteDays(y, m, d) {
        if (y < 1900 || y > 2100) return undefined;
        let total = 0;
        for (let i = 1900; i < y; i++) {
            total += isLeapYear(i) ? 366 : 365;
        }
        const daysInMonth = [0, 31, isLeapYear(y) ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
        if (d > daysInMonth[m]) return undefined; // Invalid day
        for (let i = 1; i < m; i++) {
            total += daysInMonth[i];
        }
        total += d;
        return total;
    }

    const absDays = dateToAbsoluteDays(year, month, day);
    if (absDays === undefined) return undefined;

    // Jan 1, 1900 was a Monday (absDays = 1).
    // So absDays % 7 returns: 1 = Mon, 2 = Tue, 3 = Wed, 4 = Thu, 5 = Fri, 6 = Sat, 0 = Sun
    const dayOfWeek = absDays % 7;

    return dayOfWeek === 0 || dayOfWeek === 6;
};

const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// isWeekend - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const value = applyCast(data.pre, data.src);
return out(isWeekend(value));
// ===============================================================================
// isWeekend(...) – Apply Mode
// ===============================================================================
/*
return function(value) {
   return out(isWeekend(value));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Saturday'
✅ '[example] Wednesday'
✅ Sunday
✅ Friday
✅ Invalid date returns undefined