1 files changed, 97 insertions, 0 deletions
diff --git a/scripts/apidocs/diff.ts b/scripts/apidocs/diff.ts
new file mode 100644
index 00000000..0ccdad6e
--- /dev/null
+++ b/scripts/apidocs/diff.ts
@@ -0,0 +1,97 @@
+import type { ApiDiffHashes } from './output/diff-index';
+import {
+  FILE_NAME_DOCS_DIFF_INDEX,
+  FILE_PATH_DOCS_DIFF_INDEX,
+} from './output/diff-index';
+
+/**
+ * Loads the diff index from the given source url.
+ *
+ * @param url The url to load the diff index from.
+ */
+async function loadRemote(url: string): Promise<ApiDiffHashes> {
+  return fetch(url).then((res) => {
+    if (!res.ok) {
+      throw new Error(
+        `Failed to load remote diff index from ${url}: ${res.statusText}`
+      );
+    }
+
+    return res.json() as Promise<ApiDiffHashes>;
+  });
+}
+
+/**
+ * Loads the diff index from the given local path.
+ *
+ * @param path The path to load the diff index from. Should start with `file://` for cross platform compatibility.
+ */
+async function loadLocal(path: string): Promise<ApiDiffHashes> {
+  return import(path).then((imp) => imp.default as ApiDiffHashes);
+}
+
+/**
+ * Loads the diff index from the given source.
+ * If the source starts with `https://` it will be loaded from the remote url.
+ * Otherwise it will be loaded from the local path.
+ *
+ * @param source The source to load the diff index from.
+ */
+async function load(source: string): Promise<ApiDiffHashes> {
+  return source.startsWith('https://') ? loadRemote(source) : loadLocal(source);
+}
+
+/**
+ * Returns a set of all keys from the given entries.
+ *
+ * @param entries The entries to get the keys from.
+ */
+function allKeys(
+  ...entries: ReadonlyArray<Record<string, unknown>>
+): Set<string> {
+  return new Set(entries.flatMap(Object.keys));
+}
+
+/**
+ * Compares the target (reference) and source (changed) diff index and returns the differences.
+ * The returned object contains the module names as keys and the method names as values.
+ * If the module name is `ADDED` or `REMOVED` it means that the module was added or removed in the local diff index.
+ *
+ * @param targetDiffIndex The url to the target (reference) diff index. Defaults to the next.fakerjs.dev diff index.
+ * @param sourceDiffIndex The path to the source (changed) index. Defaults to the local diff index.
+ */
+export async function diff(
+  targetDiffIndex = `https://next.fakerjs.dev/${FILE_NAME_DOCS_DIFF_INDEX}`,
+  sourceDiffIndex = `file://${FILE_PATH_DOCS_DIFF_INDEX}`
+): Promise<Record<string, ['ADDED'] | ['REMOVED'] | string[]>> {
+  const target = await load(targetDiffIndex);
+  const source = await load(sourceDiffIndex);
+
+  const diff: Record<string, string[]> = {};
+
+  for (const moduleName of allKeys(target, source)) {
+    const remoteModule = target[moduleName];
+    const localModule = source[moduleName];
+
+    if (!remoteModule) {
+      diff[moduleName] = ['ADDED'];
+      continue;
+    }
+
+    if (!localModule) {
+      diff[moduleName] = ['REMOVED'];
+      continue;
+    }
+
+    for (const methodName of allKeys(remoteModule, localModule)) {
+      const remoteMethod = remoteModule[methodName];
+      const localMethod = localModule[methodName];
+
+      if (remoteMethod !== localMethod) {
+        (diff[moduleName] ??= []).push(methodName);
+      }
+    }
+  }
+
+  return diff;
+}