bug fix

src/Store.js

@@ -1,5 +1,5 @@
 import { SingularEventEmitter } from 'secure-event-emitter'
-import { isFunction, eq } from './utils'
+import { isFunction, eq, memoizeByArgs } from './utils'
 
 
 class Store {
@@ -26,7 +26,11 @@ class Store {
     }
 
     subscribe = (cb) => {
-        const _cb = () => cb(this.state, this.prevState)
+        cb = memoizeByArgs(cb)
+        const _cb = () => {
+            cb(this.state, this.prevState)
+        }
+
         this.#emitter.on(_cb)
         return () =>  this.#emitter.off(_cb)
     }

src/utils.js

@@ -1,3 +1,36 @@
 export const isFunction = (x) => typeof x === 'function'
 export const eq = (x, y) => (x === y) || (x !== x && y !== y)
+export const memoizeByArgs = (fn) => {
+    let lastArgs;
+    let lastResult;
 
+    const memoFn = (...args) => {
+        if (!lastArgs || !isSameArgs(lastArgs, args)) {
+            lastResult = fn(...args);
+        }
+        lastArgs = args;
+        return lastResult;
+    };
+    memoFn.clearCache = () => {
+        lastArgs = undefined;
+        lastResult = undefined;
+    };
+    return memoFn;
+};
+
+
+
+
+
+
+const isSameArgs = (args1, args2) => {
+    if (args1.length !== args2.length) {
+        return false;
+    }
+    for (let i = 0; i < args1.length; ++i) {
+        if (!eq(args1[i], args2[i])) {
+            return false;
+        }
+    }
+    return true;
+};