# Load a JavaScript UDF library

> Register User-Defined Functions written in JavaScript with FalkorDB using falkor.register()

- Skill: `falkordb/load-a-javascript-udf-library` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add falkordb/load-a-javascript-udf-library`
- Raw SKILL.md: https://api.skillmd.com/api/skills/falkordb/load-a-javascript-udf-library/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: falkordb (https://skillmd.com/u/falkordb)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/falkordb/load-a-javascript-udf-library

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# Load a JavaScript UDF library

Register User-Defined Functions (UDFs) written in JavaScript with FalkorDB.

## Usage

Use the `falkor.register()` function within JavaScript code to register UDFs, then load the library using the FalkorDB client.

## Example

```python
from falkordb import FalkorDB

db = FalkorDB(host='localhost', port=6379)
lib = "StringUtils"
script = """
function UpperCaseOdd(s) {
  return s.split('')
    .map((c, i) => i % 2 !== 0 ? c.toUpperCase() : c)
    .join('');
};

falkor.register('UpperCaseOdd', UpperCaseOdd);
"""

db.udf_load(lib, script)
```

## Notes

- UDFs must be written in JavaScript
- Use `falkor.register()` to make functions available in Cypher queries
- The library name (`lib`) is used as a namespace for the functions
- UDFs are stored in FalkorDB and persist across restarts
- UDFs must be pure functions without side effects