perf(okam-core): optimize array splice operation

packages/okam-core/src/extend/data/observable/array.js

@@ -58,12 +58,20 @@ export const observableArray = {
 
     splice(observer, rawSplice, ...args) {
         let rawData = observer.rawData;
-        rawSplice.apply(rawData, args);
 
-        let result = rawSplice.apply(this, args);
-        observer.set(null, rawData);
-
-        return result;
+        if (args.length === 3 && args[1] === 1) {
+            // splice(idx, 1, newValue) is the same as arr[idx] = newValue
+            let delIdx = args[0];
+            let lastIdx = rawData.length - 1;
+            let upIdx = delIdx > lastIdx ? (lastIdx + 1) : delIdx;
+            observer.set(upIdx, args[2]);
+        }
+        else {
+            rawSplice.apply(rawData, args);
+            observer.set(null, rawData);
+        }
+
+        return rawSplice.apply(this, args);
     },
 
     sort(observer, rawSort, ...args) {

packages/okam-core/test/tasks/extend/data/observable/array.spec.js

@@ -6,18 +6,24 @@
 'use strict';
 
 /* eslint-disable babel/new-cap */
+/* global before:false */
 
 import assert from 'assert';
 import expect, {createSpy} from 'expect';
 import MyApp from 'core/swan/App';
 import {clearBaseCache} from 'core/helper/factory';
 import observable from 'core/extend/data/observable';
 import {fakeComponent, fakeAppEnvAPIs} from 'test/helper';
+import {resetObservableArray} from './helper';
 
 describe('observable array', function () {
     let MyComponent;
     let restoreAppEnv;
 
+    before('init observable array', function () {
+        resetObservableArray();
+    });
+
     beforeEach('init global App', function () {
         clearBaseCache();
 
@@ -280,6 +286,38 @@ describe('observable array', function () {
         });
     });
 
+    it('should using array index to update when splice call has three args', function (done) {
+        MyApp.use(observable);
+        let instance = MyComponent({
+            data: {
+                a: [67, 12]
+            }
+        });
+
+        let spySetData = createSpy(() => {});
+        instance.setData = spySetData;
+
+        instance.created();
+        let result = instance.a.splice(1, 1, 23);
+        expect(result).toEqual([12]);
+        expect(instance.a).toEqual([67, 23]);
+        expect(instance.a).toEqual(instance.data.a);
+
+        result = instance.a.splice(6, 1, 54);
+        expect(result).toEqual([]);
+        expect(instance.a).toEqual([67, 23, 54]);
+        expect(instance.a).toEqual(instance.data.a);
+
+        setTimeout(() => {
+            expect(spySetData).toHaveBeenCalled();
+            assert(spySetData.calls.length === 1);
+            expect(spySetData.calls[0].arguments[0]).toEqual(
+                {'a[1]': 23, 'a[2]': 54}
+            );
+            done();
+        });
+    });
+
     it('should shift array', function (done) {
         MyApp.use(observable);
         let instance = MyComponent({