Expression
In n8n, expressions let you populate fields dynamically using JavaScript and data from previous nodes, other workflows, or the n8n environment.
On this page
Source content checked . English translation published 2026-10-27.
In business automation
An expression calculates a dynamic value from data instead of using fixed text. It is useful for mapping, calculations, and composing text, but missing fields and variable numbers of incoming items need to be handled.
Examples
These examples illustrate a possible workflow. Adapt the connections and rules to your own systems.
Business process example
The customer's name and city are combined in an installation task title. If the city is missing, the expression returns a marker for review instead of the word undefined, and the task is not shown as ready to schedule.
Relevant tools
- n8n
- Expressions let you populate fields using data from nodes at runtime.
What to check
- Test expressions with empty data and multiple items. Referring to the wrong item can combine details from different customers.