feat: add toJSON method for good stringify

Author: qfox

index.js

@@ -240,6 +240,15 @@ module.exports = class BemEntityName {
         return `BemEntityName ${stringRepresentation}`;
     }
 
+    /**
+     * Return raw data for `JSON.stringify()`.
+     *
+     * @returns {{block: string, elem: ?string, mod: ?{name: string, val: *}}}
+     */
+    toJSON() {
+        return this._data;
+    }
+
     /**
      * Determines whether specified entity is the deepEqual entity.
      *