Calculate date

The calculateDate extension calculates a date by adding or subtracting a time value from a supplied date string. It can return the result in a custom Moment.js date format or, when no output format is supplied, in the default YYYY-MM-DD format.

This is useful when a journey needs dynamic dates, such as checking tomorrow's booking date, calculating an expiry date, validating a renewal date, or preparing a date value before entering it into an application field.

Parameters:

• date required, the starting date string to calculate from. ISO 8601 input is recommended; other formats depend on Moment.js parsing behavior and the supplied dateFormat value;
• operation required, the string operation to perform. Use add or subtract;
• value required, the numeric value to add or subtract. The source converts this input using Number(value), so pass a number or numeric string;
• unit required, the Moment.js duration unit to apply, such as days, weeks, months, or years;
• dateFormat optional, the Moment.js output format string. If not provided, the extension formats the result as YYYY-MM-DD.

How to apply this to your journey

Use the extension in a journey by calling calculateDate with the execute command. Pass each value to the matching extension input using as inputName.

execute "calculateDate" using "2025-04-29" as date using "add" as operation using "1" as value using "days" as unit returning $newDate
assert $newDate equals "2025-04-30"

execute "calculateDate" using "2025-04-29" as date using "subtract" as operation using "2" as value using "weeks" as unit using "YYYY-MM-DD" as dateFormat returning $newDate
assert $newDate equals "2025-04-15"

You can also pass values from journey variables. This is useful when the base date or date adjustment is produced by another step.

execute "calculateDate" using "$baseDate" as date using "$operation" as operation using "$amount" as value using "$unit" as unit using "$outputFormat" as dateFormat returning $calculatedDate

store value "2025-04-29" in $baseDate
store value "add" in $operation
store value "1" in $amount
store value "months" in $unit
store value "YYYY-MM-DD" in $outputFormat
execute "calculateDate" using "$baseDate" as date using "$operation" as operation using "$amount" as value using "$unit" as unit using "$outputFormat" as dateFormat returning $calculatedDate

Example output when adding one month to 2025-04-29 with YYYY-MM-DD formatting:

2025-05-29

This extension requires the following resources:

• https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.2/moment.min.js 
• https://cdnjs.cloudflare.com/ajax/libs/moment-timezone/0.5.31/moment-timezone-with-data.min.js 

The extension should be configured as:

• Run asynchronously: No
• Scope: Global

Add the extension to your Virtuoso instance

Select the domain that matches your Virtuoso account.

// Last updated: 29/04/2025, 11:25:53 UTC
// Resources:
//   https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.2/moment.min.js
//   https://cdnjs.cloudflare.com/ajax/libs/moment-timezone/0.5.31/moment-timezone-with-data.min.js

function manipulateDate(date, operation, value, unit) {
    const momentDate = dateFormat ? moment(date) : moment(date, dateFormat);
    if (operation === "add") {
        return momentDate.add(value, unit).format(dateFormat ? dateFormat : "YYYY-MM-DD");
    } else if (operation === "subtract") {
        return momentDate.subtract(value, unit).format(dateFormat ? dateFormat : "YYYY-MM-DD");
    } else {
        throw new Error("Invalid operation. Use 'add' or 'subtract'.");
    }
}

/**
 * @param date The initial date string, more info visit https://momentjs.com/docs/#/parsing/
 * @param operation The operation to perform (e.g., "add", "subtract")
 * @param unit The unit of time (e.g., "days", "months", "years")
 * @param value The value to add or subtract
 * @param dateFormat optional pramater to specify date format defaults to 'YYYY-MM-DD'
 * @returns The manipulated date as a string
 * @example Execute manipulateDate("2023-01-01", "add", "5", "days") returning $result
 */
return manipulateDate(date, operation, Number(value), unit);