Make JSON.parse usage safer (#373)

* Make JSON.parse usage safer

* Fix any type

* Add readResponseJson

* Use readResponseJson

* Additional updates

* Rename files

* Add types

1 files changed, 40 insertions, 0 deletions

diff --git a/ext/js/core/json.js b/ext/js/core/json.js
new file mode 100644
index 00000000..a031f84e
--- /dev/null
+++ b/ext/js/core/json.js
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2023  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * This function is used to ensure more safe usage of `JSON.parse`.
+ * By default, `JSON.parse` returns a value with type `any`, which is easy to misuse.
+ * By changing the default to `unknown` and allowing it to be templatized,
+ * this improves how the return type is used.
+ * @template [T=unknown]
+ * @param {string} value
+ * @returns {T}
+ */
+export function parseJson(value) {
+    return JSON.parse(value);
+}
+
+/**
+ * This function is used to ensure more safe usage of `Response.json`,
+ * which returns the `any` type.
+ * @template [T=unknown]
+ * @param {Response} response
+ * @returns {Promise<T>}
+ */
+export async function readResponseJson(response) {
+    return await response.json();
+}