refactor: convert to ECMAScript where necessary

Also drop @league-of-foundry-developers/foundry-vtt-types.

src/settings.js

@@ -0,0 +1,58 @@
+// SPDX-FileCopyrightText: 2021 Johannes Loher
+//
+// SPDX-License-Identifier: MIT
+
+import { getGame } from "./utils/utils";
+
+export function registerSystemSettings() {
+    const game = getGame();
+
+    /**
+     * Track the migration version of the latest migration that has been applied.
+     */
+    game.settings.register("ds4", "systemMigrationVersion", {
+        name: "System Migration Version",
+        scope: "world",
+        config: false,
+        type: Number,
+        default: -1,
+    });
+
+    game.settings.register("ds4", "useSlayingDiceForAutomatedChecks", {
+        name: "DS4.SettingUseSlayingDiceForAutomatedChecksName",
+        hint: "DS4.SettingUseSlayingDiceForAutomatedChecksHint",
+        scope: "world",
+        config: true,
+        type: Boolean,
+        default: false,
+    });
+
+    game.settings.register("ds4", "showSlayerPoints", {
+        name: "DS4.SettingShowSlayerPointsName",
+        hint: "DS4.SettingShowSlayerPointsHint",
+        scope: "world",
+        config: true,
+        type: Boolean,
+        default: false,
+    });
+}
+
+/**
+ * @typedef DS4Settings
+ * @property {number} systemMigrationVersion
+ * @property {boolean} useSlayingDiceForAutomatedChecks
+ * @property {boolean} showSlayerPoints
+ */
+
+/**
+ * Get the current values for DS4 settings.
+ * @returns {DS4Settings}
+ */
+export function getDS4Settings() {
+    const game = getGame();
+    return {
+        systemMigrationVersion: game.settings.get("ds4", "systemMigrationVersion"),
+        useSlayingDiceForAutomatedChecks: game.settings.get("ds4", "useSlayingDiceForAutomatedChecks"),
+        showSlayerPoints: game.settings.get("ds4", "showSlayerPoints"),
+    };
+}