ts-join

Global typing utility for ReadonlyArray.join to return the value of it as a type

Without ts-join:

• join (in Array and ReadonlyArray) returns string
• join (in Array and ReadonlyArray) doesn't react if a symbol is contained inside the array the method is being applied to

With ts-join:

• arr.join(s) returns the expected result of the join operation when arr is of type readonly any[] and s is a constant string
• join (in Array and ReadonlyArray) returns never if a symbol is contained inside the array the method is being applied to

Install

npm install --save-dev @zanganken/ts-join

Usage

As a simple helper

Create a ts-join.d.ts file in your project with these contents:

// Do not add any other lines of code to this file!
import "@zanganken/ts-join";

As a dependency in your project

For these imports to work, you'll need to ensure that, in your tsconfig.json, moduleResolution is set to NodeNext, Node16 or Bundler.

Import arrayJoin() in your project and use it like this:

import { arrayJoin } from "@zanganken/ts-join/array-join";

// returns "a/b/c" as a type
const something = arrayJoin(<const>["a", "b", "c"], "/")

or

Import ArrayJoin<T, S> to use it as a type in your projects:

import { type ArrayJoin } from "@zanganken/ts-join/array-join";

// returns "a/b/c" as a type
type Something = ArrayJoin<readonly ["a", "b", "c"], "/">