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An action flow is a user-defined automated workflow. Each action flow consists of an action flow trigger, which initiates the flow, and one or more actions.

Custom code steps let you execute custom JavaScript to perform complex data transformations, formatting, and advanced logic that aren't possible with the predefined actions and steps. For example, you might use a custom code step to take information to mask sensitive parts of an email address, validate the format of an email or order ID, or even calculate future dates for follow-up reminders.

This article contains the following topics:
  • Adding and configuring custom code steps
  • Supported data types for custom code inputs and outputs
  • AI prompt templates for generating custom JavaScript code for your action flow step
  • Examples custom code steps

Adding and configuring custom code steps

If you need to execute code as part of an action flow, you can add a custom code step. See Supported data types to learn which data types are supported for inputs and outputs of custom code steps.

To add custom code to an action flow
  1. Open an action flow.
  2. In the action builder, beneath an existing step, click the Add step icon ().
  3. In the step sidebar, under Flow control and utilities, click Custom code.
  4. In the step sidebar, click Add input to add inputs for the custom code.
  5. In the step sidebar, click Add output to add at least one output.
  6. In the step sidebar, under Code, enter your custom JavaScript code.
  7. Click Save.

To ensure the custom code is working as expected, test your action flow. If you run into issues, see Troubleshooting custom code steps.

Adding inputs to custom code steps

Custom code steps can have a maximum of 25 inputs.

To add inputs to a custom code step
  1. Open an action flow.
  2. In the action builder, click on an existing custom code step or click the Add step icon () to add a custom code step.
  3. In the step sidebar, click Add input.
  4. Under Select variable, select a variable from a previous step or the action flow trigger.
    Note: The input's data type is inferred from the selected variable.
  5. Verify the input's Name value, which is automatically populated based on the selected variable but can be edited. Input names must adhere to these requirements.
  6. Click Save.

Adding outputs to custom code steps

Custom code steps must have at least 1 output and up to 25 outputs.
Note: Your custom code must return a value for each defined output.
To add outputs to a custom code step
  1. Open an action flow.
  2. In the action builder, click on an existing custom code step or click the Add step icon () to add a custom code step.
  3. In the step sidebar, click Add output.
  4. Enter a unique Name for the output.

    It must adhere to these requirements.

  5. Select the output's data Type.
  6. Click Save.

Adding your custom code

The JavaScript in custom code steps must export a function that takes an inputs object amd returns an outputs object. Each time you add a custom code step to an action flow, it is prepoulated with this framework, which you can modify, expand upon, or delete and start fresh.

Although the custom code step is designed to be as user-friendly as possible, admins might still require engineering support when implementing these steps.

Keep the following requirements, limitations, and restrictions in mind:
  • The code for a step can be a maximum of 10,000 characters.
  • Your custom code must return a value for each output defined for the step.
  • The code you use in action flows must execute quickly and use a reasonable amount of memory.
  • The following JavaScript restrictions apply:
    • The function must be synchronous. That means async, await, and promise aren't supported.
    • Network requests, such as fetch, XMLHttpRequest, and jQuery AJAX arent't supported.
    • You can't import or require external libraries or modules.
To add your custom code
  1. Open an action flow.
  2. In the action builder, click on an existing custom code step or click the Add step icon () to add a custom code step.
  3. Under Code, expand upon the provided example, delete the example and write your own logic, or use an AI prompt to generate custom code for you.
    Your code must export a function that takes an inputs object amd returns an outputs object. For example:
    // In the Inputs section for this step, add an input named status.
// In the Outputs section for this step, add a text output named message.

module.exports = (inputs) => {
// Access inputs using inputs.<name>
 const msg = 'Your text was ' + inputs.status + '.'

// This return must include all outputs.
return {
  message: msg
  }
}
    Note: As you write your code, the editor offers helpful suggestions for valid JavaScript operations. Typos and invalid code are marked with a squiggly, red underline. Hover your mouse over the underlined section to view the error message.
  4. Click Save.

Supported data types for custom code inputs and outputs

The custom code step accepts and returns the following data types, each of which appears in your code as the equivalent JavaScript type.

Input type JavaScript data type Example
Text string "Hello there!"
Number number 123, -5, 0
Decimal number 12.67, 1.0, 0.0
True/false boolean true, false
Date* string "2025-10-27"
Date and time* string

A UTC date and time

"2025-10-27T10:30:00Z"

A date and time with a time zone offset:

"2025-06-22T05:11:28+10:00"

A UTC date and time with milliseconds:

"2025-03-08T06:01:21.415Z"

A date and time with a time zone offset and milliseconds:"2025-07-23T13:33:17.031-3:00"
Text array array of strings ["Hello there!", "How are you"]
Number array array of numbers [12, 34, 56, 0]
Decimal array array of numbers [2.1, 6.3, 6.01, 0.1]
True/false array array of booleans [true, true, false]
Date array array of strings ["1997-08-29", "2004-07-25", "2011-04-21"]
Datetime array array of strings ["1977-05-25T12:45Z", "1980-05-21T15:00Z", "1983-05-25T19:30Z"]
Note: * Date and datetime inputs are provided to your code as strings. To perform date operations, convert these values to JavaScript Date objects first.
The following data types below aren’t supported as outputs. If you need to return one of these types, convert it to a string before outputting it as a Text or Text array:
  • Object
  • Object array
  • Mixed array
  • Array array

AI prompt templates for generating custom JavaScript code for your action flow step

The following prompts can be used with AI tools, such as ChatGPT, to generate code for your custom code step. The pompts include guidance about the supported data types and the required structure for the code.

Prompt 1

Write a piece of JavaScript code. The code must export a function that takes an inputs object and returns an outputs object, for example:

module.exports = (inputs) => {
let msg = "Your text was " + inputs.inputText + "."
return {
  outputMessage: msg
  }
}

Supported data types:
Strings, numbers, booleans, dates (YY-MM-DD) and datetimes (YY-MM-DDTHH:mm:SSZ) are supported.  Arrays of those are supported too.

Objects, arrays of arrays, and arrays of objects are not supported.  When used as inputs or outputs they must be stringified and passed as strings.

Check for missing or invalid data, and ensure it is handled gracefully by returning a valid output:

for strings, output the empty string ""
for numbers, output -1
for booleans, output false
for arrays, output the empty array []
for objects, output the empty object {}

Comment the code:

Include a comment at the top which briefly describes what the code does.

Include comments directing the reader to create the inputs and outputs, for example: // Make sure to create the following inputs: field_tag (Text).
In comments, refer to variable types with the following friendly names:
string: use "Date" for dates, "Date and time" for datetimes, else use "Text"
number: use "Number” or "Decimal"
boolean: use "True/False"
array: use "Number array", "Text array" etc

The code should... <DESCRIBE WHAT YOU WANT YOUR CODE TO DO HERE>

Prompt 2

Write a piece of JavaScript code. The code must export a function that takes an inputs object and returns an outputs object, for example:

module.exports = (inputs) => {
let msg = "Your text was " + inputs.inputText + "."
return {
outputMessage: msg
}
}

Supported input and output data types:
Strings, numbers, booleans, dates (YY-MM-DD) and datetimes (YY-MM-DDTHH:mm:SSZ) are supported.  Arrays of those are supported too.

Objects, arrays of arrays, and arrays of objects are not supported.  When used as inputs or outputs they must be stringified and passed as strings.

Comment the code:

Include a comment at the top which briefly describes what the code does.

Include comments directing the reader to create the inputs and outputs, for example: // Make sure to create the following inputs: field_tag (Text).
In comments, refer to variable types with the following friendly names:
string: use "Date" for dates, "Date and time" for datetimes, else use "Text"
number: use "Number" or "Decimal"
boolean: use "True/False"
array: use "Number array", "Text array" etc

The code should... <DESCRIBE WHAT YOU WANT YOUR CODE TO DO HERE>

Examples custom code steps

The following examples demonstrate how the custom code step can be used to address common automation scenarios:
  • Formatting basic ticket details into a human-readable comment
  • Calculating the next hour from now
  • Validating the formatting of an email address
  • Masking an email address
  • Mapping an internal identifier to a human-readable name
  • Checking whether any items in a list begin with specific characters
  • Comparing two lists of values
  • Finding an order ID within text
  • Generating a random number
  • Generating three random numbers between one and seven
Note: Zendesk provides these JavaScript examples for instructional purposes only. Zendesk does not guarantee compatibility with your specific use case and does not offer support for writing or debugging custom JavaScript. Always test code in a test environment first, and avoid including sensitive data.

Formatting basic ticket details into a human-readable comment

module.exports = (inputs) => {
  // This code takes text inputs 'status' and 'priority', and a number input 'ticket_id', and outputs a friendly message combining these values.

  // Make sure to create the following inputs:
  // status (Text)
  // priority (Text)
  // ticket_id (Number)

  const message = `Ticket ${inputs.ticket_id} has status ${inputs.status} and priority ${inputs.priority}.`

  // Make sure to create the following outputs:
  // message (Text)
  return {
    message,
  }
}

Calculating the next hour from now

In the example, the time is currently 2025-10-27T09:17:00Z. Therefore, the following code returns 2025-10-27T10:00:00Z.

module.exports = (inputs) => {
  // This code calculates the next full hour from the current UTC time

  // No inputs required

  // Make sure to create the following outputs:
  // nextHour (Date and time)

  // Create a Date object for the current time
  const nextHour = new Date()

  // Round up to the next hour by:
  // 1. Setting minutes, seconds, and milliseconds to 0
  nextHour.setUTCMinutes(0, 0, 0)
  // 2. Adding 1 hour
  nextHour.setUTCHours(nextHour.getUTCHours() + 1)

  return {
    nextHour: nextHour.toISOString(),
  }
}

Validating the formatting of an email address

module.exports = (inputs) => {
  // This code takes a text input 'emailAddress',
  // uses regex to do a basic check whether it is a valid email format,
  // and outputs a boolean 'emailIsValid'.

  // Make sure to create the following inputs:
  // emailAddress (Text)

  // Simple email regex pattern
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/

  const emailIsValid = emailRegex.test(inputs.emailAddress)

  // Make sure to create the following outputs:
  // emailIsValid (True/False)

  return {
    emailIsValid
  }
}

Masking an email address

This example replaces portions of an email address with asterisk characters. For example, "Could you please confirm your email address is d******n@zendesk.com?"

// This code takes an email address input and returns a masked version where the local part is partially replaced with '*', preserving the first and last characters.

// Make sure to create the following input:
// emailToMask (Text)

// Make sure to create the following output:
// maskedEmail (Text)

module.exports = (inputs) => {
  
  const [emailName, emailDomain] = inputs.emailToMask.split("@")

  let maskedEmailName = emailName

  if (emailName.length > 2) {
    maskedEmailName = emailName[0]
    maskedEmailName += "*".repeat(emailName.length-2)
    maskedEmailName += emailName[emailName.length-1]
  }

  return {
    maskedEmail: `${maskedEmailName}@${emailDomain}`
  }
}

Mapping an internal identifier to a human-readable name

Mappings like this are useful for converting internal ids, such as a dropdown ticket field’s tag, to more user-friendly names like a value shown in a dropdown.

You can use this approach for tasks such as:
  • Translating Slack channel ids to channel names
  • Converting JIRA project ids to project names
  • Mapping Zendesk ticket statuses to corresponding JIRA issue statuses
const optionMap = {
  option_01_ivory: 'ivory',
  option_02_cream: 'cream',
  option_03_white: 'white',
  option_04_bone: 'bone',
}

module.exports = (inputs) => {
  // This code takes a text input 'optionTag',
  // and outputs the corresponding 'optionName' based on a predefined mapping.
  // If the input is missing or does not match any tag, it returns an empty string.

  // Make sure to create the following inputs:
  // optionTag (Text)

  const optionName = optionMap[inputs.optionTag] || ''

  // Make sure to create the following outputs:
  // optionName (Text)

  return {
    optionName,
  }
}

Checking whether any items in a list begin with specific characters

This example checks whether any items in a list begin with specific characters. For example, if you're searching for items beginning with “customer” and your list of tags contains [“critical_bug”, “customer_24601”, “escalation”], the result would be true because “customer_24601” begins with “customer”.

module.exports = (inputs) => {
  // This code takes a text array 'tags' and a text string 'searchTerm',
  // and outputs a boolean 'matchFound' indicating whether any tag begins with the searchTerm.

  // Make sure to create the following inputs:
  // tags (Text array)
  // searchTerm (Text)

  const matchFound = inputs.tags.some(tag => tag.startsWith(inputs.searchTerm))

  // Make sure to create the following outputs:
  // matchFound (True/False)

  return {
    matchFound
  }
}

Comparing two lists of values

This example compares two lists and removes all values from the first list that are also present in the second.

For example, given a list of ticket CCs and a list of disallowed users, any disallowed users found in the CC list will be excluded from the output list (cleanCCs). This method can also be used to filter out tags that should be removed from a ticket or user.

module.exports = (inputs) => {
  // This code takes two number arrays: ticketCCs and disallowedUsers,
  // and outputs a number array cleanCCs which includes only those items from ticketCCs that are NOT in disallowedUsers.

  // Make sure to create the following inputs:
  // ticketCCs (Number array)
  // disallowedUsers (Number array)

  const cleanCCs = inputs.ticketCCs.filter(cc => !inputs.disallowedUsers.includes(cc))

  // Make sure to create the following outputs:
  // cleanCCs (Number array)

  return {
    cleanCCs,
  }
}

Finding an order ID within text

This example extracts an order ID from a string of text, such as a ticket comment. You can adjust the regular expression (/GO-\d{8,9}/) as needed to match your specific order ID format.

// Regex for order number: "GO-" followed by 8 or 9 digits
const ORDER_NUMBER_REGEX = /GO-\d{8,9}/

// Searches comment for order number and returns it if found.
const findOrderNumber = comment => comment.match(ORDER_NUMBER_REGEX)[0]

module.exports = (inputs) => {
  // This code uses regex to look for an orderNumber with pattern "GO-" followed by 8 or 9 digits

  // Make sure to create the following inputs:
  // commentBody (Text)

  const orderNumber = findOrderNumber(inputs.commentBody)

  // Make sure to create the following outputs:
  // orderNumber (Text)
  // matchFound (True/False)

  return {
    orderNumber,
    matchFound: Boolean(orderNumber),
  }
}

Generating a random number

This example generates a random number within the boundaries you specify. You can change the value 52 to set your desired upper limit for the random number.

module.exports = (inputs) => {
  // This code outputs a random integer number between 1 and 52 inclusive.

  // No inputs required.

  // Make sure to create the following outputs:
  // randomNumber (Number)

  const randomNumber = Math.floor(Math.random() * 52) + 1

  return {
    randomNumber
  }
}

Generating three random numbers between one and seven

The following example returns three random numbers as individual outputs:
module.exports = (inputs) => {
  // This code outputs three unique random integer numbers between 1 and 7 inclusive.

  // No inputs required.

  // Make sure to create the following outputs:
  // randomNumber1 (Number)
  // randomNumber2 (Number)
  // randomNumber3 (Number)

  const numbers = []
  while (numbers.length < 3) {
    const candidate = Math.floor(Math.random() * 7) + 1
    if (!numbers.includes(candidate)) {
      numbers.push(candidate)
    }
  }

  return {
    randomNumber1: numbers[0],
    randomNumber2: numbers[1],
    randomNumber3: numbers[2]
  }
}
This example returns three random numbers in an array rather than individually:
module.exports = (inputs) => {
  // This code outputs an array of three unique random numbers between 1 and 7 inclusive.

  // No inputs required.

  // Make sure to create the following outputs:
  // randomNumbers (Number array)

  const numbers = []
  while (numbers.length < 3) {
    const candidate = Math.floor(Math.random() * 7) + 1
    if (!numbers.includes(candidate)) {
      numbers.push(candidate)
    }
  }

  return {
    randomNumbers: numbers
  }
}
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