feat: customAttributes, close #36

Author: Scrum

lib/index.js

@@ -5,13 +5,14 @@ const selectorParser = require('postcss-selector-parser');
 const nameGenerators = require('./name-generators');
 
 class MinifyClassnames {
-  constructor({genNameClass, genNameId, filter} = {}) {
+  constructor({genNameClass, genNameId, filter, customAttributes = []} = {}) {
     this.filter = filter || /^.js-/;
     // TODO: Pass a seed for emojinamestring, make this better
     this.genNameClass = this.getNameGenerator(genNameClass, 7);
     this.genNameId = this.getNameGenerator(genNameId, 5);
     this.classMap = {};
     this.idMap = {};
+    this.customAttributes = customAttributes;
   }
 
   getNameGenerator(value, seed) {
@@ -60,6 +61,28 @@ class MinifyClassnames {
 
   minifyElements(tree) {
     return tree.walk(node => {
+      if (node.attrs && this.customAttributes.length > 0) {
+        const attributes = Object.keys(node.attrs);
+
+        this.customAttributes
+          .filter(attribute => attributes.includes(attribute))
+          .forEach(attributes => {
+            node.attrs[attributes] = node.attrs[attributes]
+              .split(/\s+/)
+              .map(value => {
+              // NOTE: This removes classes that don't match any in our CSS
+                if (this.isClassFiltered(value)) {
+                  return value;
+                }
+
+                return this.classMap[value] || '';
+              })
+              .filter(Boolean)
+              .join(' ')
+              .trim();
+          });
+      }
+
       if (node.attrs && node.attrs.class) {
         let classes = node.attrs.class;
         node.attrs.class = classes