Script step

  • Release version: Zurich
  • Updated July 31, 2025
  • 5 minutes to read
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    Summary of Script step

    The Script step in Workflow Studio allows ServiceNow customers to add custom JavaScript code within reusable actions, enabling behavior beyond the capabilities of core action steps. This feature is available to users with theactiondesignerrole and is accessible as an action step in Workflow Studio. It supports execution on the ServiceNow instance, MID Server, or using core JavaScript, depending on the selected runtime environment. Integration Hub activation is required to access certain runtime and MID Server options.

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    Key Features

    • Runtime Selection: Choose where the script executes—on the instance (default), on a MID Server, or using vanilla core JavaScript without ServiceNow APIs.
    • MID Server Configuration: When selecting the MID Server runtime, you can specify which MID Server or cluster to use via auto-selection, specific MID Server, or MID Cluster. You can also filter eligible MID Servers by application support and capabilities. Connection aliases simplify credential management across environments.
    • Input and Output Variables: Define named input and output variables to map data between Workflow Studio and the script. Inputs allow scripts to consume data from prior steps or action inputs, while outputs expose results to subsequent steps.
    • Script Structure: Scripts access inputs and outputs via global objects named inputs and outputs. Variables should avoid reserved system names to prevent conflicts. Script outputs are converted to strings, with JSON data handled as strings or parsed within the script.
    • Error Handling: Configure the action’s behavior if the script step fails, choosing to either continue or trigger error evaluation.

    Practical Use and Benefits

    ServiceNow customers can use the Script step to incorporate custom logic tailored to unique business needs that core steps do not cover. By mapping inputs and outputs, scripts integrate seamlessly with other Workflow Studio steps, enabling complex workflows. Runtime options provide flexibility in accessing ServiceNow APIs or external resources via MID Servers. Using connection aliases enhances security and simplifies maintenance across environments.

    For example, scripts can build JSON payloads dynamically for use in subsequent REST steps (which require Integration Hub). This capability allows customers to efficiently prepare data for external integrations within workflows.

    Requirements and Considerations

    • Integration Hub subscription is required to run scripts on MID Servers and to use REST steps.
    • Users must have the actiondesigner role to create or modify Script steps.
    • Ensure scripts avoid reserved system field names for input/output variables.
    • Workflow Studio executes scripts in the domain context where the workflow is initiated, respecting domain separation rules.

    Add custom JavaScript to execute within a reusable action. While most core actions and steps fit common use cases, you can build a Script step to execute behavior not satisfied by the core steps.

    Roles and availability

    Available as an Workflow Studio action step. Users with the action_designer role can create a custom action with one or more action steps.
    Note:
    Integration Hub See Request Integration Hub for information about Integration Hub usage and subscriptions.

    Fields

    The Script step includes separate input and output variables that enable you to map JavaScript data to Workflow Studio data. By defining input and output variables within the step, you can define what Workflow Studio data is available within your script, and which scripting variables are available to other steps in your action.

    Field Description
    Required Runtime
    The runtime environment required to support the script. Choices include:
    • Instance: The action step runs the script from instance. Select this option when the script needs access to the ServiceNow API or instance data. This is the default value.
    • MID: The action step runs the script from the MID Server. Select this option when the script needs access to MID Server script files and APIs. Selecting this option displays the Select MID Server Using field.
    • Vanilla (Core JavaScript): The action step runs the script from either the instance or MID Server. Select this option when the script only needs the core JavaScript APIs and not the ServiceNow API or instance data.

    The runtime you select determines the JavaScript objects and methods displayed in the Context-sensitive help.

    Note:
    This field is only visible when Integration Hub is activated.
    Select MID Server Using
    Specify the MID Server selection process to use. Choices include:
    • Any MID. The system runs the action step from any available MID Server.
    • Use Connection Alias. The system runs the action using the connection alias you specify. Selecting this option displays the Connection Alias field.
    • Use Inline Selection. The system runs the action using the connection details you specify in the action. Selecting this option displays the Host, MID Application, and Capabilities fields.
    Note:
    This field is only visible when Integration Hub is activated, and you select MID from Required Runtime.
    Connection Alias Connection & Credential alias record that the system uses to run the action step. Users with the flow_designer or admin role can create or select an associated Connection record. Using an alias eliminates the need to configure multiple credentials and connection information profiles when using an action in multiple environments. Likewise, if the connection information changes, you don't need to update your custom action. To learn more about connections and credentials, see credentials, connections, and aliases. Only aliases of connection type Basic are supported.
    Note:
    This field is only visible when Integration Hub is activated, and you select Use Connection Alias from Select MID Server Using.
    Host The fully-qualified domain name of the MID Server where the system runs the action step. For example, mid-server.domain.com.
    Note:
    This field is only visible when Integration Hub is activated, and you select Use Inline Selection from Select MID Server Using.
    MID Selection Option to select a specific MID Server or MID Cluster. Choose any one of the following options.
    • Auto-Select MID Server: Your ServiceNow instance selects the MID Server without manual input.
    • Specific MID Server: Your ServiceNow instance uses MID Server that you specify.
    • Specific MID Cluster: Your ServiceNow instance uses the MID Cluster that you specify.

      A MID Cluster is a group of MID Servers that enables your ServiceNow instance to handle multiple integrations, and improve integration speed. For more information, see Configure a MID Server cluster.

    This field is available when MID is selected from the Required Runtime list, and Use Inline Selection is selected from the Select MID Server Using list.
    MID Cluster Data pill for the MID Cluster you want to use. This field is available when MID is selected from the Required Runtime list, and Use Inline Selection is selected from the Select MID Server Using list.
    MID Application Specify the application the MID Server must support to be eligible for selection. The system runs the action step from a MID Server that supports the selected application. This field is only visible when Integration Hub is activated, Auto-Select MID Server is selected from the MID Selection list, and you select Use Inline Selection from Select MID Server Using.
    Capabilities Capabilities the MID Server must support to be eligible for selection. The system runs the action step from a MID Server that supports the selected capabilities. This field is only visible when Integration Hub is activated, Auto-Select MID Server is selected from the MID Selection list, and you select Use Inline Selection from Select MID Server Using.
    Specific MID Server Data pill of the required MID Server. This field is only visible when Integration Hub is activated, Specific MID Server is selected from the MID Selection list, and you select Use Inline Selection from Select MID Server Using.
    Input variables Name-value pairs that represent data from the action, enabling you to use action inputs and data from other steps within a script.
    Script
    Script that executes within the action. To access input and output variables in your script, use the global objects inputs and outputs. For example, inputs.myVariable.
    Note:
    Script step input and output names can't include any of the following reserved system names:
    • sys_id
    • sys_created_by
    • sys_created_on
    • sys_updated_on
    • sys_updated_by
    • sys_mod_count
    In general, don't create a variable that has the same name as a system field. The Script step may confuse such an input variable for a field name and use the wrong value.
    The Script step always converts data stored in the inputs and outputs global objects into strings. If your Script step needs to work with JSON data, you can use the inputs global object to convert the JSON data into a string. Alternatively, you can define a JavaScript variable as a string rather than a JavaScript object. For example, this script illustrates two ways you can output JSON data.
    (function execute(inputs, outputs) {
  outputs.json_object_1 = inputs.json_input;
  var array_of_objs = '[{"name1":"value1"}, {"id":"abcd"}]';
  outputs.json_object_2 = array_of_objs;
})(inputs, outputs);

    By default, Workflow Studio run scripts on the instance. To run script from a MID Server requires an Integration Hub subscription.

    Workflow Studio runs script from the domain from which it is triggered or initiated. See Domain separation and Workflow Studio.

    For available classes and methods, see the JavaScript API context-sensitive help or the API reference.
    Output variables Map JavaScript output to Workflow Studio data pills. Define output variables when you want other steps in the action to use the script output.

    Action error evaluation

    If this step fails
    Data type: Choice

    Option to continue running the next step or go to error evaluation. To use the step status code or message for a custom action error condition, see Action error evaluation.

    Example

    This example builds a JSON payload that can be easily updated or changed and added to a subsequent REST step.

    Note:
    REST step is not available in the base system and requires the ServiceNow® Integration Hub subscription.

    Example Script step in an action.

    By creating an output variable that represents the payload, you can drag the [Payload] data pill into the REST step Body field.