---
id: introduction
title: Introduction
description: A Jest transformer with source map support that lets you use Jest to test projects written in TypeScript.
slug: /
---

`ts-jest` is a Jest [transformer](https://jestjs.io/docs/next/code-transformation#writing-custom-transformers) with source map support that lets you use Jest to test projects written in TypeScript.

It supports all features of TypeScript including type-checking. [Read more about Babel7 + `preset-typescript` **vs** TypeScript (and `ts-jest`)](babel7-or-ts).

:::important

We are not doing semantic versioning and `23.10` is a re-write, run `npm i -D ts-jest@"<23.10.0"` to go back to the previous version

:::
