convert csrfToken constan variable

EnvelopeGenerator.Web/wwwroot/js/network.js

@@ -1,11 +1,7 @@
 /**
  * Fetches CSRF Token from page
- * @returns
  */
-function getCSRFToken() {
-    const token = document.getElementsByName('__RequestVerificationToken')[0].value
-    return { 'X-XSRF-TOKEN': token }
-}
+const csrfToken = { 'X-XSRF-TOKEN': document.getElementsByName('__RequestVerificationToken')[0].value };
 
 /**
  * Save signature data to server
@@ -13,7 +9,7 @@ function getCSRFToken() {
  * @param {any} annotations
  */
 function postEnvelope(envelopeKey, annotations) {
-    const token = getCSRFToken()
+    const token = csrfToken
     const options = {
         credentials: 'include',
         method: 'POST',