diff --git a/ts/domtools.classes.domtools.ts b/ts/domtools.classes.domtools.ts
index c7e8c60..cfe36cc 100644
--- a/ts/domtools.classes.domtools.ts
+++ b/ts/domtools.classes.domtools.ts
@@ -49,6 +49,11 @@ export class DomTools {
 
   private runOnceTrackerStringMap = new Stringmap();
   private runOnceResultMap = new FastMap();
+  /**
+   * run a function once and always get the Promise of the first execution
+   * @param identifierArg
+   * @param funcArg
+   */
   public async runOnce<T>(identifierArg: string, funcArg: () => Promise<T>) {
     const runningId = `${identifierArg}+runningCheck`;
     if(!this.runOnceTrackerStringMap.checkString(identifierArg)) {