---
title: "isExpressionFilter | JavaScript maps SDK"
description: "Documentation for MapTiler SDK"
---

> For AI agents: a documentation index is available at [/llms.txt](https://docs.maptiler.com/llms.txt). Markdown versions of all pages are available by appending .md to any URL.

# Function isExpressionFilter

-   isExpressionFilter(filter: any): filter is [ExpressionFilterSpecification](https://docs.maptiler.com/sdk-js/api-reference/types/ExpressionFilterSpecification/)[](#isexpressionfilter)
    
    #### Parameters
    
    -   filter: any
    
    #### Returns filter is [ExpressionFilterSpecification](https://docs.maptiler.com/sdk-js/api-reference/types/ExpressionFilterSpecification/)