add method removeCSSRule with test

src/utils.js

@@ -180,6 +180,18 @@ function buildCSSRule(rule, styleMap, cssRulesString = '') {
   return `${cssRulesString}${getCSSRuleBlock(rule, styleMap)}`;
 }
 
+function removeCSSRule(rule, cssRulesString = '') {
+  const rulePatternStr = `${escapeRegExp(rule)} {([^}]*)}`;
+  const rulePattern = new RegExp(rulePatternStr, 'g');
+  let output = cssRulesString;
+
+  if (cssRulesString && cssRulesString.match(rulePattern)) {
+    output = cssRulesString.replace(rulePattern, '');
+  }
+
+  return output.trim();
+}
+
 export default {
   getHeaderHTML,
   getBodyHTML,
@@ -191,6 +203,7 @@ export default {
   namespaceSelector,
   getCSSString,
   buildCSSRule,
+  removeCSSRule,
   makeDataAttributeString,
   getDefault,
   escapeRegExp

test/utils.spec.js

@@ -5,6 +5,7 @@ import {
 	makeDataAttributeString,
 	getCSSString,
   buildCSSRule,
+  removeCSSRule
 } from '../src/utils.js';
 
 chai.expect();
@@ -67,4 +68,14 @@ describe('#utils', () => {
         .to.be.equal('.test { width: 5px; height: 19px; margin-top: 3px; }.test2 { height: 45px; }');
     });
   });
+
+  describe('removeCSSRule', () => {
+    it('should remove the css rule based on the selector', () => {
+      const rule = '.test';
+      const cssRuleString = `.test {margin-top: 2px;} .test2 {color: blue;}`;
+
+      expect(removeCSSRule(rule, cssRuleString))
+        .to.be.equal('.test2 {color: blue;}');
+    })
+  })
 });