feat: Implement trim() to remove unused space

android/src/main/cpp/MmkvHostObject.cpp

@@ -221,6 +221,20 @@ jsi::Value MmkvHostObject::get(jsi::Runtime& runtime, const jsi::PropNameID& pro
     });
   }
 
+  if (propName == "trim") {
+    // MMKV.trim()
+    return jsi::Function::createFromHostFunction(runtime,
+                                                 jsi::PropNameID::forAscii(runtime, funcName),
+                                                 0,
+                                                 [this](jsi::Runtime& runtime,
+                                                        const jsi::Value& thisValue,
+                                                        const jsi::Value* arguments,
+                                                        size_t count) -> jsi::Value {
+      instance->trim();
+      return jsi::Value::undefined();
+    });
+  }
+
   if (propName == "recrypt") {
     // MMKV.recrypt(encryptionKey)
     return jsi::Function::createFromHostFunction(runtime,

ios/MmkvHostObject.mm

@@ -227,6 +227,22 @@
     });
   }
 
+  if (propName == "trim") {
+    // MMKV.trim()
+    return jsi::Function::createFromHostFunction(runtime,
+                                                 jsi::PropNameID::forAscii(runtime, funcName),
+                                                 0,
+                                                 [this](jsi::Runtime& runtime,
+                                                        const jsi::Value& thisValue,
+                                                        const jsi::Value* arguments,
+                                                        size_t count) -> jsi::Value {
+        NSLog(@"Before: %zu / %zu", [instance actualSize], [instance totalSize]);
+      [instance trim];
+        NSLog(@"After: %zu / %zu", [instance actualSize], [instance totalSize]);
+      return jsi::Value::undefined();
+    });
+  }
+
   if (propName == "recrypt") {
     // MMKV.recrypt(encryptionKey)
     return jsi::Function::createFromHostFunction(runtime,

src/MMKV.ts

@@ -88,6 +88,10 @@ interface MMKVInterface {
    * Delete all keys.
    */
   clearAll: () => void;
+  /**
+   * Trim unused space on the storage file
+   */
+  trim: () => void;
   /**
    * Sets (or updates) the encryption-key to encrypt all data in this MMKV instance with.
    *
@@ -117,6 +121,7 @@ export type NativeMMKV = Pick<
   | 'getNumber'
   | 'getString'
   | 'set'
+  | 'trim'
   | 'recrypt'
 >;
 
@@ -212,6 +217,10 @@ export class MMKV implements MMKVInterface {
     const func = this.getFunctionFromCache('recrypt');
     return func(key);
   }
+  trim(): void {
+    const func = this.getFunctionFromCache('trim');
+    return func();
+  }
 
   toString(): string {
     return `MMKV (${this.id}): [${this.getAllKeys().join(', ')}]`;

src/createMMKV.mock.ts

@@ -22,6 +22,7 @@ export const createMockMMKV = (): NativeMMKV => {
     },
     getAllKeys: () => Array.from(storage.keys()),
     contains: (key) => storage.has(key),
+    trim: () => {},
     recrypt: () => {
       console.warn('Encryption is not supported in mocked MMKV instances!');
     },

src/createMMKV.web.ts

@@ -46,6 +46,7 @@ export const createMMKV = (config: MMKVConfiguration): NativeMMKV => {
     },
     getAllKeys: () => Object.keys(storage()),
     contains: (key) => storage().getItem(key) != null,
+    trim: () => {},
     recrypt: () => {
       throw new Error('`recrypt(..)` is not supported on Web!');
     },