Feat: optimizedMapping always have values

README.md

@@ -34,7 +34,13 @@ rcs.fillLibraries(fs.readFileSync('./src/styles.css', 'utf8'));
 rcs.selectorsLibrary.setExclude('selector-to-ignore');
 ```
 
-2. Rewrite all files
+2. Optimize the selectors compression (optional)
+
+```js
+rcs.optimize();
+```
+
+3. Rewrite all files
 
 > **Note:** Do not forget to replace your CSS file
 

__tests__/optimize/optimize.ts

@@ -7,12 +7,36 @@ beforeEach(() => {
   rcs.keyframesLibrary.reset();
   rcs.selectorsLibrary.setAlphabet('#abcdefghijklmnopqrstuvwxyz');
   rcs.selectorsLibrary.reset();
+  rcs.statistics.load(undefined);
 });
 
-test('should ignore everything without selectors', () => {
+test('should ignore everything without selectors but with statistics', () => {
   const input = { };
 
   rcs.mapping.load(input);
+  rcs.statistics.load({
+    ids: {
+      unused: [],
+      usageCount: {
+        test: 2,
+      },
+    },
+    classes: {
+      unused: [],
+      usageCount: {
+        'my-selector': 2,
+      },
+    },
+    keyframes: {
+      unused: [],
+      usageCount: {},
+    },
+    cssVariables: {
+      unused: [],
+      usageCount: {},
+    },
+  });
+
   rcs.optimize();
 
   expect(rcs.mapping.generate()).toEqual(input);

lib/optimize/optimize.ts

@@ -19,7 +19,12 @@ const optimize = (): void => {
   // sorting
   // renaming into new mapping
   const separateMapping = separateMappingSelectors(mapping.selectors);
-  const optimizedMapping: { [key in keyof ReturnType<typeof generateStatistics>]?: string[] } = {};
+  const optimizedMapping: { [key in keyof ReturnType<typeof generateStatistics>]: string[] } = {
+    ids: [],
+    classes: [],
+    keyframes: [],
+    cssVariables: [],
+  };
 
   // optimize each library
   Object.entries(separateMapping).forEach(([key, selectors]) => {
@@ -37,10 +42,6 @@ const optimize = (): void => {
 
   // fill libraries with optimized mapping
   Object.entries(optimizedMapping).forEach(([key, selectors]) => {
-    if (!selectors) {
-      return;
-    }
-
     switch (key) {
       case 'ids':
         selectors.forEach((selector) => selectorsLibrary.set(`#${selector}`));