---
title: "ConcatArray | 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.

# Interface ConcatArray<T>

interface ConcatArray<[T](#t)\> {  
    [length](#length): number;  
    [join](#join-1)(separator?: string): string;  
    [slice](#slice-1)(start?: number, end?: number): [T](#t)\[\];  
    readonly \[n: number\]: [T](#t);  
}

#### Type Parameters

-   T

#### Indexable

-   readonly \[n: number\]: [T](#t)
    

##### Index

### Properties[](#properties)

[length](#length)

### Methods[](#methods)

[join](#join) [slice](#slice)

## Properties[](#properties-1)

### `Readonly`length[](#length)

length: number

## Methods[](#methods-1)

### join[](#join)

-   join(separator?: string): string[](#join-1)
    
    #### Parameters
    
    -   `Optional`separator: string
    
    #### Returns string
    

### slice[](#slice)

-   slice(start?: number, end?: number): [T](#t)\[\][](#slice-1)
    
    #### Parameters
    
    -   `Optional`start: number
    -   `Optional`end: number
    
    #### Returns [T](#t)\[\]