feature: @putout/plugin-minify: merge-loops: add

packages/plugin-minify/README.md

@@ -28,6 +28,7 @@ npm i @putout/plugin-putout -D
             "mangleClassNames": true
         }],
         "minify/merge-variables": "on",
+        "minify/merge-loops": "on",
         "minify/remove-var-undefined": "on",
         "minify/remove-return-undefined": "on",
         "minify/simplify-floor": "on",
@@ -329,6 +330,27 @@ var a;
 var b;
 ```
 
+## merge-loops
+
+Check out in 🐊[**Putout Editor**](https://putout.cloudcmd.io/#/gist/c9b77f37202389d30924135c2db3db9e/345edfc73c65b6cdf53c9b5e68bf689e4128291f).
+
+### ❌ Example of incorrect code
+
+```js
+for (const aa of a)
+    d.push(aa);
+
+for (const bb of b)
+    d.push(bb);
+```
+
+### ✅ Example of correct code
+
+```js
+for (const aa of [...a, ...b])
+    d.push(aa);
+```
+
 ## simplify-floor
 
 Not only shorter, but faster:

packages/plugin-minify/lib/merge-loops/fixture/merge-loops-fix.js

@@ -0,0 +1,7 @@
+for (const aa of [...a, ...b])
+    d.push(aa);
+
+b.forEach((bb) => d.push(bb));
+
+for (const aa of [...a, ...b])
+    d.push(aa);

packages/plugin-minify/lib/merge-loops/fixture/merge-loops.js

@@ -0,0 +1,11 @@
+a.forEach(aa=>d.push(aa)),
+b.forEach(bb=>d.push(bb));
+
+b.forEach(bb=>d.push(bb));
+
+
+for (const aa of a)
+    d.push(aa);
+
+for (const bb of b)
+    d.push(bb);

packages/plugin-minify/lib/merge-loops/index.js

@@ -0,0 +1,40 @@
+import {
+    operator,
+    template,
+} from 'putout';
+
+const {
+    remove,
+    getTemplateValues,
+    compare,
+} = operator;
+
+const FOR = 'for (const __a of __b)__c(__e)';
+
+const createLoop = template(`for (const  __a of [...__b, ...__z])__c(__e)`, {
+    placeholderPattern: /^__[a-z]$/,
+});
+
+export const report = () => `Merge loops`;
+
+export const replace = () => ({
+    '__a.forEach((__b) => __e(__b)),__c.forEach((__d) => __e(__d))': 'for (const  __b of [...__a, ...__c])__e(__b)',
+    [FOR]: ({__a, __b, __c, __e}, path) => {
+        const next = path.getNextSibling();
+
+        if (compare(next, FOR)) {
+            const {__b: __z} = getTemplateValues(next, FOR);
+            remove(next);
+
+            return createLoop({
+                __a,
+                __b,
+                __c,
+                __e,
+                __z,
+            });
+        }
+
+        return path;
+    },
+});

packages/plugin-minify/lib/merge-loops/index.spec.js

@@ -0,0 +1,19 @@
+import {createTest} from '@putout/test';
+import * as plugin from './index.js';
+
+const test = createTest(import.meta.url, {
+    printer: 'putout',
+    plugins: [
+        ['merge-loops', plugin],
+    ],
+});
+
+test('packages: merge-loops: report', (t) => {
+    t.report('merge-loops', `Merge loops`);
+    t.end();
+});
+
+test('packages: merge-loops: transform', (t) => {
+    t.transform('merge-loops');
+    t.end();
+});

packages/plugin-minify/test/fixture/merge-loops-fix.js

@@ -0,0 +1,9 @@
+(a.forEach((A) => d.push(A)), b.forEach((_) => d.push(_)));
+
+b.forEach((B) => d.push(B));
+
+for (const c of a)
+    d.push(c);
+
+for (const C of b)
+    d.push(C);

packages/plugin-minify/test/fixture/merge-loops.js

@@ -0,0 +1,11 @@
+a.forEach(aa=>d.push(aa)),
+b.forEach(bb=>d.push(bb));
+
+b.forEach(bb=>d.push(bb));
+
+
+for (const aa of a)
+    d.push(aa);
+
+for (const bb of b)
+    d.push(bb);

packages/plugin-minify/test/minify.js

@@ -97,3 +97,8 @@ test('plugin-minify: transform: if', (t) => {
     t.transform('if');
     t.end();
 });
+
+test('plugin-minify: transform: merge-loops', (t) => {
+    t.transform('merge-loops');
+    t.end();
+});