javascript-esm: Adopt .tool-versions toolchain declaration for javascript-esm

javascript-esm/.tool-versions

@@ -0,0 +1,2 @@
+node 22
+yarn 3

javascript-esm/README.md

@@ -1,15 +1,30 @@
 # Javascript ESM
 
-Skeleton project for Javascript (ESM) with Jest for testing.
+Skeleton project for Javascript (ESM).
 
-## Usage
-- `./script/setup` to install dependencies
-- `./script/test` to run the tests
-- `./script/start` to run the index.js file
+## Prerequisites
+
+The toolchain this project needs is declared in [`.tool-versions`](./.tool-versions):
+
+```
+node 22
+yarn 3
+```
 
+Install those however you prefer, as long as they end up on your `PATH`. The quickest route is
+[mise](https://mise.jdx.dev/), which reads the file for you:
+
+```sh
+mise install
+```
+
+## Usage
+- `./script/setup` to fetch dependencies
+- `./script/test` to run the tests, or `./script/test --watch` to re-run them on every change
+- `./script/start` to run the app
 
 ## Structure
 - Code located in [`index.js`](./src/index.js)
 - Tests located in [`index.test.js`](./src/index.test.js)
 
-However, you're free to organise your code as you like. 
+However, you're free to organise your code as you like.

javascript-esm/script/setup

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
-set -e
+set -euo pipefail
+
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
 
 yarn

javascript-esm/script/start

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
-set -e
+set -euo pipefail
+
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
 
 yarn start