fix: Optimize and modernize code

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

lib/index.ts

@@ -148,11 +148,11 @@ export const imagePath = (app: string, file: string) => {
  * @return {string} URL with webroot for a file in an app
  */
 export const generateFilePath = (app: string, type: string, file: string) => {
-	const isCore = window?.OC?.coreApps?.indexOf(app) !== -1
+	const isCore = window?.OC?.coreApps?.includes(app)
 	const isPHP = file.slice(-3) === 'php'
 	let link = getRootUrl()
 	if (isPHP && !isCore) {
-		link += '/index.php/apps/' + app
+		link += `/index.php/apps/${app}`
 		if (file !== 'index.php') {
 			link += '/'
 			if (type) {
@@ -163,22 +163,17 @@ export const generateFilePath = (app: string, type: string, file: string) => {
 	} else if (!isPHP && !isCore) {
 		link = getAppRootUrl(app)
 		if (type) {
-			link += '/' + type + '/'
+			link += `/${type}/`
 		}
-		if (link.substring(link.length - 1) !== '/') {
+		if (link.at(-1) !== '/') {
 			link += '/'
 		}
 		link += file
 	} else {
 		if ((app === 'settings' || app === 'core' || app === 'search') && type === 'ajax') {
-			link += '/index.php/'
-		} else {
-			link += '/'
-		}
-		if (app !== '') {
-			app += '/'
-			link += app
+			link += '/index.php'
 		}
+		link += `/${app}`
 		if (type) {
 			link += type + '/'
 		}