clean code

resource/js/util/markdown-it/plantuml.js

@@ -5,6 +5,8 @@ export default class PlantUMLConfigurer {
   constructor(crowi) {
     this.crowi = crowi;
     const config = crowi.getConfig();
+
+    this.deflate = require('markdown-it-plantuml/lib/deflate.js');
     this.serverUrl = config.env.PLANTUML_URI || 'http://plantuml.com';
 
     this.generateSource = this.generateSource.bind(this);
@@ -17,9 +19,8 @@ export default class PlantUMLConfigurer {
   }
 
   generateSource(umlCode) {
-    var deflate = require('markdown-it-plantuml/lib/deflate.js');
-    var zippedCode =
-      deflate.encode64(deflate.zip_deflate('@startuml\n' + umlCode + '\n@enduml', 9));
+    const zippedCode =
+      this.deflate.encode64(this.deflate.zip_deflate('@startuml\n' + umlCode + '\n@enduml', 9));
     return urljoin(this.serverUrl, 'plantuml', 'svg' , zippedCode);
   }
 }