> For the complete documentation index, see [llms.txt](https://docs.justransform.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.justransform.com/development/business-processes/components-of-business-process/map-mapchain-jtscript-custom-function.md).

# Map/MapChain/JTScript (Custom Function)

Among all of the components within the Business Process, Map/MapChain/JTScript (Custom Function) - **CF** component is the most important component of, the process. It can contain logic for ANY to ANY Transformation, Validation, Split Merge and any other message processing requirement

To **CF** to a business process drag and drop it from the left panel. You will have the following window

![image-20200513-141623.png](blob:https://justransform.atlassian.net/d6dc9da0-5d58-4db2-8bdd-3296099c51d7#media-blob-url=true\&id=753931c8-94a2-4fdc-882f-acaea08c14bf\&collection=contentId-18219077\&contextId=18219077\&height=912\&width=1260\&alt=)![](https://2064141549-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbabsiNJvoWQygNRGHzGx%2Fuploads%2Foud1Fo0nnMGvaizdUVuj%2Fimage.png?alt=media\&token=3568f7fd-df96-47ff-adcf-33c25f37a639)

At this junction, you have 3 options

1. You can inject a JTMap created by using Mapper
2. You can inject a JTMapChain created by using Map chain
3. You can write your custom script JT Scripts

Once you drag and drop the custom function you will be able to see all the pre-defined JT Utils, which is useful in importing the Lookup Tables, Global variables, Mappers, and many more.

<figure><img src="https://2064141549-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbabsiNJvoWQygNRGHzGx%2Fuploads%2Fd8dEDqyXFix1JLWp6PhP%2Fimage.png?alt=media&amp;token=0cad2e87-354d-4ada-988a-a9012754ac61" alt=""><figcaption></figcaption></figure>

You can find the list of all the pre-defined functions on the JT Utils page.

Also, it has pre-defined variables.&#x20;

For example:- Transaction Id

It also has the For-loop code in the Customfunction.

<figure><img src="https://2064141549-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbabsiNJvoWQygNRGHzGx%2Fuploads%2F9bZtXSx1pCzPQipxTpul%2Fimage.png?alt=media&amp;token=f7eff591-ae89-4ac5-8765-989b2447e280" alt=""><figcaption></figcaption></figure>