---
title: "ProjectionSpecification | 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.

# Type Alias ProjectionSpecification

type ProjectionSpecification \= {  
    [type](#type)?: [PropertyValueSpecification](https://docs.maptiler.com/sdk-js/api-reference/types/PropertyValueSpecification/)<[ProjectionDefinitionSpecification](https://docs.maptiler.com/sdk-js/api-reference/types/ProjectionDefinitionSpecification/)\>;  
}

##### Index

### Properties[](#properties)

[type?](#type)

## Properties[](#properties-1)

### `Optional`type[](#type)

type?: [PropertyValueSpecification](https://docs.maptiler.com/sdk-js/api-reference/types/PropertyValueSpecification/)<[ProjectionDefinitionSpecification](https://docs.maptiler.com/sdk-js/api-reference/types/ProjectionDefinitionSpecification/)\>

The projection definition type. Can be specified as a string, a transition state, or an expression.

#### Default[](#default)

```typescript
"mercator"
```