Meta: Add lint-prettier.sh

This is a script similar to the clang-format one to ensure prettier
formatting of most JavaScript files.

.prettierignore

@@ -0,0 +1 @@
+Base/home/anon/Source/js

Meta/lint-prettier.sh

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+#!/bin/bash
+
+set -e
+
+script_path=$(cd -P -- "$(dirname -- "$0")" && pwd -P)
+cd "${script_path}/.." || exit 1
+
+if ! command -v prettier >/dev/null 2>&1 ; then
+ echo "prettier is not available. Either skip this script, or install prettier."
+ exit 1
+fi
+
+if ! prettier --version | grep -qF '2.' ; then
+ echo "You are using '$(prettier --version)', which appears to not be prettier 2."
+ exit 1
+fi
+
+if [ "$#" -eq "0" ]; then
+ mapfile -t files < <(
+ git ls-files \
+ --exclude-from .prettierignore \
+ -- \
+ '*.js'
+ )
+else
+ files=()
+ for file in "$@"; do
+ if [[ "${file}" == *".js" ]]; then
+ files+=("${file}")
+ fi
+ done
+fi
+
+if (( ${#files[@]} )); then
+ prettier --check "${files[@]}"
+else
+ echo "No .js files to check."
+fi