Fix Javascript issue on non sqlite databases

When a non sqlite database is used, loading the admin interface fails
because the backup button is not generated.
This PR is solves it by checking if the elements are valid.

Also made some other changes and fixed some eslint errors.
Showing `_post` errors is better now.

Update jquery to latest version.

Fixes #3166

src/static/scripts/admin_settings.js

@@ -1,6 +1,8 @@
 "use strict";
+/* eslint-env es2017, browser */
+/* global _post:readable, BASE_URL:readable */
 
-function smtpTest() {
+function smtpTest(event) {
     event.preventDefault();
     event.stopPropagation();
     if (formHasChanges(config_form)) {
@@ -41,7 +43,7 @@ function getFormData() {
     return data;
 }
 
-function saveConfig() {
+function saveConfig(event) {
     const data = JSON.stringify(getFormData());
     _post(`${BASE_URL}/admin/config/`,
         "Config saved correctly",
@@ -51,7 +53,7 @@ function saveConfig() {
     event.preventDefault();
 }
 
-function deleteConf() {
+function deleteConf(event) {
     event.preventDefault();
     event.stopPropagation();
     const input = prompt(
@@ -68,7 +70,7 @@ function deleteConf() {
     }
 }
 
-function backupDatabase() {
+function backupDatabase(event) {
     event.preventDefault();
     event.stopPropagation();
     _post(`${BASE_URL}/admin/config/backup_db`,
@@ -94,24 +96,26 @@ function formHasChanges(form) {
 
 // This function will prevent submitting a from when someone presses enter.
 function preventFormSubmitOnEnter(form) {
-    form.onkeypress = function(e) {
-        const key = e.charCode || e.keyCode || 0;
-        if (key == 13) {
-            e.preventDefault();
-        }
-    };
+    if (form) {
+        form.addEventListener("keypress", (event) => {
+            if (event.key == "Enter") {
+                event.preventDefault();
+            }
+        });
+    }
 }
 
 // This function will hook into the smtp-test-email input field and will call the smtpTest() function when enter is pressed.
 function submitTestEmailOnEnter() {
     const smtp_test_email_input = document.getElementById("smtp-test-email");
-    smtp_test_email_input.onkeypress = function(e) {
-        const key = e.charCode || e.keyCode || 0;
-        if (key == 13) {
-            e.preventDefault();
-            smtpTest();
-        }
-    };
+    if (smtp_test_email_input) {
+        smtp_test_email_input.addEventListener("keypress", (event) => {
+            if (event.key == "Enter") {
+                event.preventDefault();
+                smtpTest(event);
+            }
+        });
+    }
 }
 
 // Colorize some settings which are high risk
@@ -124,11 +128,11 @@ function colorRiskSettings() {
     });
 }
 
-function toggleVis(evt) {
+function toggleVis(event) {
     event.preventDefault();
     event.stopPropagation();
 
-    const elem = document.getElementById(evt.target.dataset.vwPwToggle);
+    const elem = document.getElementById(event.target.dataset.vwPwToggle);
     const type = elem.getAttribute("type");
     if (type === "text") {
         elem.setAttribute("type", "password");
@@ -146,9 +150,11 @@ function masterCheck(check_id, inputs_query) {
     }
 
     const checkbox = document.getElementById(check_id);
-    const onChange = onChanged(checkbox, inputs_query);
-    onChange(); // Trigger the event initially
-    checkbox.addEventListener("change", onChange);
+    if (checkbox) {
+        const onChange = onChanged(checkbox, inputs_query);
+        onChange(); // Trigger the event initially
+        checkbox.addEventListener("change", onChange);
+    }
 }
 
 const config_form = document.getElementById("config-form");
@@ -172,9 +178,18 @@ document.addEventListener("DOMContentLoaded", (/*event*/) => {
         password_toggle_btn.addEventListener("click", toggleVis);
     });
 
-    document.getElementById("backupDatabase").addEventListener("click", backupDatabase);
-    document.getElementById("deleteConf").addEventListener("click", deleteConf);
-    document.getElementById("smtpTest").addEventListener("click", smtpTest);
+    const btnBackupDatabase = document.getElementById("backupDatabase");
+    if (btnBackupDatabase) {
+        btnBackupDatabase.addEventListener("click", backupDatabase);
+    }
+    const btnDeleteConf = document.getElementById("deleteConf");
+    if (btnDeleteConf) {
+        btnDeleteConf.addEventListener("click", deleteConf);
+    }
+    const btnSmtpTest = document.getElementById("smtpTest");
+    if (btnSmtpTest) {
+        btnSmtpTest.addEventListener("click", smtpTest);
+    }
 
     config_form.addEventListener("submit", saveConfig);
 });