Refactoring: Split shared types into seperate modules and document alot.

server/shared/utils/json.ts

@@ -0,0 +1,42 @@
+/**
+ * Utility functions for JSON.
+ */
+import { isJSONValue, JSONObject, JSONValue } from "../types";
+
+/**
+ * Parses the given `string` and converts it into a {@link JSONValue}.
+ *
+ * For the string to be considered valid JSON it has to satisfy the requirements for {@link JSON.parse}.
+ *
+ * @param str - `string` to parse.
+ * @returns The parsed integer JSON value.
+ * @throws {@link SyntaxError} - If the given `string` does not represent a valid JSON value.
+ */
+export function parseJSON(str: string): JSONValue {
+    const json = JSON.parse(str);
+    if (!isJSONValue(json)) {
+        throw new Error("Invalid JSON returned. Should never happen.");
+    }
+    return json;
+}
+
+/**
+ * Removes `undefined` fields from the given JSON'ish object to make it a valid {@link JSONObject}.
+ *
+ * Note: This only happens for fields directly belonging to the given object. No recursive cleanup is performed.
+ *
+ * @param obj - Object to remove `undefined` fields from.
+ * @returns Cleaned up JSON object.
+ */
+export function filterUndefinedFromJSON(obj: {
+    [key: string]: JSONValue | undefined;
+}): JSONObject {
+    const result: JSONObject = {};
+    for (const [key, value] of Object.entries(obj)) {
+        if (value !== undefined) {
+            result[key] = value;
+        }
+    }
+
+    return result;
+}