---
title: Advanced topics
description: How to interpret long task spans in the UI, Using with TypeScript, Initial Page load transaction names, Custom Transactions. 
url: https://www.elastic.co/docs/reference/apm/agents/rum-js/advanced-topics
products:
  - APM Agent
  - APM RUM JavaScript Agent
applies_to:
  - Elastic Cloud Serverless: Unavailable
  - Elastic Stack: Generally available
---

# Advanced topics
- [How to interpret long task spans in the UI](https://www.elastic.co/docs/reference/apm/agents/rum-js/longtasks)
- [Using with TypeScript](https://www.elastic.co/docs/reference/apm/agents/rum-js/typescript)
- [Initial Page load transaction names](https://www.elastic.co/docs/reference/apm/agents/rum-js/custom-transaction-name)
- [Custom Transactions](https://www.elastic.co/docs/reference/apm/agents/rum-js/custom-transactions)