diff --git a/jupyter-openbis-extension/static/connectionDialog.js b/jupyter-openbis-extension/static/connectionDialog.js
index 177372e0264f6654aca73113ffdd85b8b66d7e35..3663a50b07f77948887efafbcdfe1edb25ae5e2d 100644
--- a/jupyter-openbis-extension/static/connectionDialog.js
+++ b/jupyter-openbis-extension/static/connectionDialog.js
@@ -7,34 +7,34 @@ define(
     ],
     function (dialog, $, state, connections) {
 
-        var currentDownloadPath = null
+        let currentDownloadPath = null;
 
         function show_available_connections(env, data, conn_table) {
             if (!currentDownloadPath) {
                 currentDownloadPath = data.cwd
             }
 
-            var table = document.createElement("TABLE")
+            let table = document.createElement("TABLE");
             table.className = 'table-bordered table-striped table-condensed'
-            var thead = table.createTHead()
-            var thead_row = thead.insertRow(0)
-            var titles = ['', 'Name', 'URL', 'Status', 'Username / Password']
+            let thead = table.createTHead();
+            let thead_row = thead.insertRow(0)
+            let titles = ['', 'Name', 'URL', 'Status', 'Username / Password']
             for (title of titles) {
                 thead_row.insertCell().textContent = title
             }
 
             tbody = table.createTBody()
 
-            var getConnectionByName = function(name) {
-            	for (connection of data.connections) {
-            		if(connection.name === name) {
-            			return connection;
-            		}
-            	}
-            }
-            
+            let getConnectionByName = function (name) {
+                for (connection of data.connections) {
+                    if (connection.name === name) {
+                        return connection;
+                    }
+                }
+            };
+
             for (connection of data.connections) {
-                var conn = document.createElement("INPUT")
+                let conn = document.createElement("INPUT")
                 conn.type = "radio"
                 conn.name = "connection_name"
                 conn.value = connection.name
@@ -46,28 +46,28 @@ define(
                 	state.connection.candidateDTO = getConnectionByName(state.connection.candidateName);
                 }
 
-                var row = tbody.insertRow()
+                let row = tbody.insertRow()
                 row.insertCell().appendChild(conn)
-                var nameCell = row.insertCell()
+                let nameCell = row.insertCell()
                 nameCell.textContent = connection.name
                 nameCell.onclick = function () {
-                    var radio = this.parentElement.firstElementChild.firstElementChild
+                    let radio = this.parentElement.firstElementChild.firstElementChild
                     radio.checked = 1
                     state.connection.candidateName = radio.value
                     state.connection.candidateDTO = getConnectionByName(state.connection.candidateName);
                 }
-                var urlCell = row.insertCell()
+                let urlCell = row.insertCell()
                 urlCell.textContent = connection.url
                 urlCell.onclick = function () {
-                    var radio = this.parentElement.firstElementChild.firstElementChild
+                    let radio = this.parentElement.firstElementChild.firstElementChild
                     radio.checked = 1
                     state.connection.candidateName = radio.value
                     state.connection.candidateDTO = getConnectionByName(state.connection.candidateName);
                 }
 
-                var status_cell = row.insertCell()
+                let status_cell = row.insertCell()
 
-                var status_badge = document.createElement("SPAN")
+                let status_badge = document.createElement("SPAN")
                 status_badge.id = connection.name + "-badge"
                 status_badge.textContent = connection.status
                 if (connection.status === "connected") {
@@ -77,14 +77,14 @@ define(
                 }
                 status_cell.appendChild(status_badge)
 
-                var username = document.createElement("INPUT")
+                let username = document.createElement("INPUT")
                 username.type = "text"
                 username.name = "username"
                 username.autocomplete = "on"
                 username.value = connection.username
                 username.setAttribute("form", connection.name)
 
-                var password = document.createElement("INPUT")
+                let password = document.createElement("INPUT")
                 password.type = "password"
                 password.name = "password"
                 password.autocomplete = "current-password"
@@ -92,11 +92,11 @@ define(
                 password.setAttribute("form", connection.name)
 
                 // Username / Password form
-                var pwform = document.createElement("FORM")
+                let pwform = document.createElement("FORM")
                 pwform.id = connection.name
                 pwform.onsubmit = function (event) {
-                    var form_data = new FormData(this)
-                    var status_badge = document.getElementById(this.id + "-badge")
+                    let form_data = new FormData(this)
+                    let status_badge = document.getElementById(this.id + "-badge")
                     connections.connect(env, this.id,
                             form_data.get("username"), form_data.get("password")
                         )
@@ -128,7 +128,7 @@ define(
                 }
 
 
-                var connect_button = document.createElement("BUTTON")
+                let connect_button = document.createElement("BUTTON")
                 connect_button.className = "btn btn-primary btn-xs"
                 connect_button.textContent = "connect"
 
@@ -136,11 +136,11 @@ define(
                 pwform.appendChild(password)
                 pwform.appendChild(connect_button)
 
-                var pwCell = row.insertCell()
+                let pwCell = row.insertCell()
                 pwCell.appendChild(pwform)
 
                 pwCell.onclick = function () {
-                    var radio = this.parentElement.firstElementChild.firstElementChild
+                    let radio = this.parentElement.firstElementChild.firstElementChild
                     radio.checked = 1
                     state.connection.candidateName = radio.value
                     state.connection.candidateDTO = getConnectionByName(state.connection.candidateName);
@@ -148,12 +148,12 @@ define(
             }
 
             // add row for new connection
-            var row = tbody.insertRow()
+            let row = tbody.insertRow()
 
-            var conn_form = document.createElement("FORM")
+            let conn_form = document.createElement("FORM")
             conn_form.id = "new_connection"
             conn_form.onsubmit = function (event) {
-                var inputs = document.querySelectorAll("input[form=new_connection]")
+                let inputs = document.querySelectorAll("input[form=new_connection]")
 
                 data = {}
                 for (input of inputs) {
@@ -176,7 +176,7 @@ define(
                     })
                 return false
             }
-            var conn_name = document.createElement("INPUT")
+            let conn_name = document.createElement("INPUT")
             conn_name.type = "input"
             conn_name.name = "connection_name"
             conn_name.setAttribute("form", conn_form.id)
@@ -184,7 +184,7 @@ define(
             row.insertCell().appendChild(conn_form)
             row.insertCell().appendChild(conn_name)
 
-            var conn_url = document.createElement("INPUT")
+            let conn_url = document.createElement("INPUT")
             conn_url.type = "input"
             conn_url.name = "url"
             conn_url.setAttribute("form", conn_form.id)
@@ -192,21 +192,21 @@ define(
             row.insertCell().appendChild(conn_url)
             row.insertCell()
 
-            var username = document.createElement("INPUT")
+            let username = document.createElement("INPUT")
             username.autocomplete = "off"
             username.type = "text"
             username.name = "username"
             username.setAttribute("form", conn_form.id)
             username.placeholder = "username"
-            var password = document.createElement("INPUT")
+            let password = document.createElement("INPUT")
             password.type = "password"
             password.name = "password"
             password.autocomplete = "new-password"
             password.setAttribute("form", conn_form.id)
-            var create_btn = document.createElement("BUTTON")
+            let create_btn = document.createElement("BUTTON")
             create_btn.setAttribute("form", conn_form.id)
             create_btn.textContent = "create"
-            var uname_pw_cell = row.insertCell()
+            let uname_pw_cell = row.insertCell()
             uname_pw_cell.appendChild(username)
             uname_pw_cell.appendChild(password)
             uname_pw_cell.appendChild(create_btn)
@@ -224,13 +224,12 @@ define(
             help_index: '',
             handler: function (env) {
                 conn_table = document.createElement("DIV")
-                var dst_title = document.createElement("STRONG")
+                let dst_title = document.createElement("STRONG")
                 dst_title.textContent = "DataSet type"
-                var dataset_types = document.createElement("SELECT")
+                let dataset_types = document.createElement("SELECT")
                 dataset_types.id = "dataset_type"
                 dataset_types.className = "form-control select-xs"
 
-                var input_fields = document.createElement("DIV")
                 conn_table.id = "openbis_connections"
 
                 connections.list(env)
@@ -241,7 +240,7 @@ define(
                         alert(data.status)
                     })
 
-                var uploadDialogBox = $('<div/>').append(conn_table)
+                let uploadDialogBox = $('<div/>').append(conn_table)
 
                 function onOk() {
                     state.connection.name = state.connection.candidateName