Thunder Client: simplest way to add script to request

I try to figure out how to add custom code to my request similar way to pre-request script in Postman like:

const items = JSON.parse(pm.collectionVariables.get('items'))

const randomItem = _.sample(items)

pm.variables.set('randomItemId', randomItem.id)
pm.variables.set('randomItem', JSON.stringify(randomItem));

I know that for 03 2023 importing external libraries is in beta, but let's assume it works ok.

I understand that I need to create filter:

First question: where is option to create one? I wish it will be separated form my project code.

Second question: can I have filter code directly in my request (visible to quickly check what happening in request)? Or I need to create filters for every request where I need new custom code 😔

I tried follow docs but there is no clear information where add files for filters: https://github.com/rangav/thunder-client-support/blob/master/docs/filters.md

I partially figured it out because it looks like scripts are injected on Collection level.

Prerequisites - navigate to Thunder Client:

1. Create Environment (Env tab -> menu -> New Environment) let's call it baseEnv
2. In baseEnv set empty v variable and Save
3. Create Collection (Collection tab -> menu -> New Collection) let's call it myCol
4. In myCol go to menu -> Settings -> Environment and attach Environment baseEnv

Create script:

1. Decide where you will keep the scripts (i.e. separate repository)
2. Create file i.e. script.js
3. Add function to script:

   async function testFunc() {
       console.log("Test log message");
       return "TEST";
   }
   
   module.exports = [testFunc];
   

To add custom script to Collection:

1. Go to Collections and find your Collection
2. Open Collection menu (...)
3. Open Setting tab
4. Choose file with script
5. Save

Use script:

1. Crete request in Collection (menu -> New Request)
2. Url: https://httpbin.org/anything
3. In Headers add header A-test with value: {{v | testFunc}}
4. Send request!

Result:

If script is not loaded and function was not executed try:

• load script again and save
• type expression {{v | testFunc}} and save

Extend scripts:

1. Place there files with 2 scripts:
2. Example file with script https://github.com/rangav/thunder-client-support/blob/master/docs/custom-filters.js
3. Example file with types https://github.com/rangav/thunder-client-support/blob/master/docs/tc-types.d.ts