> For the complete documentation index, see [llms.txt](https://academy.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://academy.pentaho.com/pentaho-data-integration/data-integration/enrich-data/scripting/modified-javascript-value.md).
# Modified JavaScript Value
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**Workshop - Modified JavaScript value**
The Modified Java Script Expression step in Pentaho Data Integration (PDI) allows users to execute custom JavaScript code to transform and manipulate data within a transformation. This step provides a powerful scripting environment where you can write JavaScript functions to perform complex calculations, data validations, string manipulations, and conditional logic that might be difficult or impossible to achieve with standard PDI steps.
The step takes input fields from the data stream, processes them through your custom JavaScript code, and outputs the results as new fields or modified existing fields. It's particularly useful for implementing business rules, data cleansing operations, or complex transformations that require programming logic beyond what built-in PDI steps can provide.
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Modified JavaScript Value
***
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{% tab title="1. Generate rows " %}
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**Generate rows**
The Generate Rows step in Pentaho Data Integration (PDI) is a data generation component that creates synthetic data rows based on user-defined specifications. This step allows you to generate test data, sample datasets, or placeholder records by defining field names, data types, and value ranges or patterns.
You can specify how many rows to generate and configure various parameters like random number ranges, date intervals, or fixed values for each field. It's particularly useful for testing transformations, creating mock data for development purposes, or generating large datasets for performance testing without requiring an external data source.
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Generate rows
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**Modified JavaScript value**
The Modified JavaScript value step provides a user interface for building JavaScript expressions that you can use to modify your data. The code you type in the script area is executed once for each input row.
* The transform allows multiple scripts in a single transform instance.
* The JavaScript step is not an input step and therefore requires an input stream from the pipeline.
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Modified JavaScript value
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Here the name of the var = name of output data stream field. In some cases you will need to 'escape' the character.
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