feat: add safelist keyframes and css variables

- add safelist for keyframes (#418, #439)
- add safelist for css variables

packages/purgecss/__tests__/safelist.test.ts

@@ -126,3 +126,53 @@ describe("safelist option: greedy", () => {
     );
   });
 });
+
+describe("safelist option: keyframes", () => {
+  let purgedCSS: string;
+  beforeAll(async () => {
+    const resultsPurge = await new PurgeCSS().purge({
+      content: [`${ROOT_TEST_EXAMPLES}safelist/safelist_keyframes.html`],
+      css: [`${ROOT_TEST_EXAMPLES}safelist/safelist_keyframes.css`],
+      safelist: {
+        keyframes: [/^scale/, "spin"],
+      },
+      keyframes: true,
+    });
+    purgedCSS = resultsPurge[0].css;
+  });
+
+  it("finds safelisted keyframes", () => {
+    findInCSS(
+      expect,
+      ["@keyframes scale", "@keyframes scale-down", "@keyframes spin"],
+      purgedCSS
+    );
+  });
+
+  it("excludes non-safelisted keyframes", () => {
+    notFindInCSS(expect, ["flash"], purgedCSS);
+  });
+});
+
+describe("safelist option: variables", () => {
+  let purgedCSS: string;
+  beforeAll(async () => {
+    const resultsPurge = await new PurgeCSS().purge({
+      content: [`${ROOT_TEST_EXAMPLES}safelist/safelist_css_variables.html`],
+      css: [`${ROOT_TEST_EXAMPLES}safelist/safelist_css_variables.css`],
+      safelist: {
+        variables: [/^--b/, "--unused-color"],
+      },
+      variables: true,
+    });
+    purgedCSS = resultsPurge[0].css;
+  });
+
+  it("finds safelisted css variables", () => {
+    findInCSS(expect, ["--unused-color", "--button-color"], purgedCSS);
+  });
+
+  it("excludes non-safelisted css variables", () => {
+    notFindInCSS(expect, ["--tertiary-color:"], purgedCSS);
+  });
+});

packages/purgecss/__tests__/test_examples/safelist/safelist_css_variables.css

@@ -0,0 +1,22 @@
+:root {
+    --primary-color: blue;
+    --secondary-color: indigo;
+    --tertiary-color: aqua;
+    --unused-color: violet;
+    --used-color: rebeccapurple;
+    --accent-color: orange;
+  }
+
+  .button {
+    --button-color: var(--tertiary-color);
+    --border-color: linear-gradient(to top, var(--secondary-color), var(--used-color, white));
+
+    background-color: var(--primary-color);
+    color: var(--accent-color);
+    border-color: var(--border-color);
+  }
+
+  .button:focus {
+    background-color: var(--accent-color);
+    color: var(--primary-color);
+  }

packages/purgecss/__tests__/test_examples/safelist/safelist_css_variables.html

@@ -0,0 +1 @@
+<button class="button">Click me!</button>

packages/purgecss/__tests__/test_examples/safelist/safelist_keyframes.css

@@ -0,0 +1,61 @@
+@keyframes bounce {
+    from, 20%, 53%, 80%, to {
+        animation-timing-function: cubic-bezier(0.3, 0.1, 0.9, 1.000);
+        transform: translate3d(1, 1, 0);
+    }
+}
+
+.bounce {
+    -webkit-animation-name: bounce;
+    animation-name: bounce;
+    -webkit-transform-origin: center bottom;
+    transform-origin: center bottom;
+}
+
+@keyframes flash {
+    from, 50%, to {
+        opacity: 1;
+    }
+
+    25%, 75% {
+        opacity: 0.5;
+    }
+}
+
+.flash {
+    animation: flash
+}
+
+@keyframes scale {
+    from {
+        transform: scale(1);
+    }
+
+    to {
+        transform: scale(2);
+    }
+}
+
+@keyframes scale-down {
+    from {
+        transform: scale(2);
+    }
+
+    to {
+        transform: scale(1);
+    }
+}
+
+@keyframes spin {
+    from {
+        transform: rotate(0deg);
+    }
+
+    to {
+        transform: rotate(360deg);
+    }
+}
+
+.scale-spin {
+    animation: spin 300ms linear infinite forwards,scale 300ms linear infinite alternate;
+}

packages/purgecss/__tests__/test_examples/safelist/safelist_keyframes.html

@@ -0,0 +1,2 @@
+<div class="bounce">
+</div>

packages/purgecss/src/VariablesStructure.ts

@@ -1,4 +1,5 @@
 import postcss from "postcss";
+import { StringRegExpArray } from "./types";
 
 class VariableNode {
   public nodes: VariableNode[] = [];
@@ -13,6 +14,7 @@ class VariableNode {
 class VariablesStructure {
   public nodes: Map<string, VariableNode> = new Map();
   public usedVariables: Set<string> = new Set();
+  public safelist: StringRegExpArray = [];
 
   addVariable(declaration: postcss.Declaration): void {
     const { prop } = declaration;
@@ -63,12 +65,20 @@ class VariablesStructure {
     for (const used of this.usedVariables) {
       this.setAsUsed(used);
     }
-    for (const [, declaration] of this.nodes) {
-      if (!declaration.isUsed) {
+    for (const [name, declaration] of this.nodes) {
+      if (!declaration.isUsed && !this.isVariablesSafelisted(name)) {
         declaration.value.remove();
       }
     }
   }
+
+  isVariablesSafelisted(variable: string): boolean {
+    return this.safelist.some((safelistItem) => {
+      return typeof safelistItem === "string"
+        ? safelistItem === variable
+        : safelistItem.test(variable);
+    });
+  }
 }
 
 export default VariablesStructure;

packages/purgecss/src/index.ts

@@ -542,6 +542,18 @@ class PurgeCSS {
     return sources;
   }
 
+  /**
+   * Check if the keyframe is safelisted with the option safelist keyframes
+   * @param keyframesName name of the keyframe animation
+   */
+  private isKeyframesSafelisted(keyframesName: string): boolean {
+    return this.options.safelist.keyframes.some((safelistItem) => {
+      return typeof safelistItem === "string"
+        ? safelistItem === keyframesName
+        : safelistItem.test(keyframesName);
+    });
+  }
+
   /**
    * Check if the selector is safelisted with the option safelist standard
    * @param selector css selector
@@ -590,7 +602,11 @@ class PurgeCSS {
             ...userOptions,
             safelist: standardizeSafelist(userOptions.safelist),
           };
-    const { content, css, extractors } = this.options;
+    const { content, css, extractors, safelist } = this.options;
+
+    if (this.options.variables) {
+      this.variablesStructure.safelist = safelist.variables || [];
+    }
 
     const fileFormatContents = content.filter(
       (o) => typeof o === "string"
@@ -637,7 +653,10 @@ class PurgeCSS {
    */
   public removeUnusedKeyframes(): void {
     for (const node of this.atRules.keyframes) {
-      if (!this.usedAnimations.has(node.params)) {
+      if (
+        !this.usedAnimations.has(node.params) &&
+        !this.isKeyframesSafelisted(node.params)
+      ) {
         node.remove();
       }
     }