diff --git a/client/src/modules/cart.ts b/client/src/modules/cart.ts
index 0f21f83..d177d1a 100644
--- a/client/src/modules/cart.ts
+++ b/client/src/modules/cart.ts
@@ -4,26 +4,29 @@ import * as I from "../types/types";
 import * as UI from "./ui";
 import * as Events from "./events";
 
-export function addItem(inSeatObj: I.JSCSelectedSeat) {
-    const color = `#${XMLHelper.getVenuePricescalePropertyByPricescaleID("color", inSeatObj.data.seatsObj.id[0])}`;
-    const category = XMLHelper.getVenuePricescalePropertyByPricescaleID("desc", inSeatObj.data.seatsObj.id[0]);
-    const seat = config.state.layoutRows[inSeatObj.id][5];
-    const row = config.state.layoutRows[inSeatObj.id][4];
-    const sectionID = config.state.layoutRows[inSeatObj.id][3];
-    const sectionDesc = XMLHelper.getSectionDescBySectionID(sectionID);
-    const seatStr = `${sectionDesc}<br/>Reihe ${row} Platz ${seat}`;
-    const buyerTypes: (string | undefined)[][] | undefined = getBuyerTypesByPricescaleID(inSeatObj.data.seatsObj.id[0]);
-    const cartId = `cartItem-${inSeatObj.id}`;
-    const dropdownBuyerTypesSelector = `#${cartId} .dropdownBuyerTypes`;
+type buyerType = (string | undefined)[][] | undefined;
+type buyerTypeArr = (string | undefined)[];
 
-    appendHTML(cartId, color, category, seatStr);
-    addDropdownBuyerTypesOptions(buyerTypes, dropdownBuyerTypesSelector);
+export function addItem(inSeatObj: I.JSCSelectedSeat): void { 
+    const color: string = `#${XMLHelper.getVenuePricescalePropertyByPricescaleID("color", inSeatObj.data.seatsObj.id[0])}`;
+    const category: string | undefined = XMLHelper.getVenuePricescalePropertyByPricescaleID("desc", inSeatObj.data.seatsObj.id[0]);
+    const seat: string = config.state.layoutRows[inSeatObj.id][5];
+    const row: string = config.state.layoutRows[inSeatObj.id][4];
+    const sectionID: string = config.state.layoutRows[inSeatObj.id][3];
+    const sectionDesc: string | undefined = XMLHelper.getSectionDescBySectionID(sectionID);
+    const seatStr: string | undefined = `${sectionDesc}<br/>Reihe ${row} Platz ${seat}`;
+    const buyerTypes: buyerType = getBuyerTypesByPricescaleID(inSeatObj.data.seatsObj.id[0]);
+    const cartID: string = `cartItem-${inSeatObj.id}`;
+    const dropdownBuyerTypesSelector: string = `#${cartID} .dropdownBuyerTypes`;
+
+    appendHTML(cartID, color, category, seatStr);
+    addDropdownBuyerTypeOptions(buyerTypes, dropdownBuyerTypesSelector);
     Events.addCartDropdownBuyerTypes(dropdownBuyerTypesSelector, inSeatObj);
 }
 
-function appendHTML(inCartId: string, inColor: string, inCategory: string | undefined, inSeatStr: string) {
+function appendHTML(inCartID: string, inColor: string, inCategory: string | undefined, inSeatStr: string): void {
     jQuery("#cartItemHTML .fl-html").append(`
-    <div class="cartItem" id="${inCartId}">
+    <div class="cartItem" id="${inCartID}">
         <div class="cartItemColoredSquare" style="background: ${inColor};"></div>
         <div class="cartItemCategory">${inCategory}</div>
         <h5 class="cartItemSeat">${inSeatStr}</h5>
@@ -32,26 +35,29 @@ function appendHTML(inCartId: string, inColor: string, inCategory: string | unde
 }
 
 // todo: generalize dropdown fill options
-function addDropdownBuyerTypesOptions(inBuyerTypes: (string | undefined)[][] | undefined, inSelector: string) {
+function addDropdownBuyerTypeOptions(inBuyerTypes: buyerType, inSelector: string) {
     if (!inBuyerTypes)
         return;
 
-    const dropdownBuyerTypes = jQuery(inSelector).get(0);
+    const dropdownBuyerTypes: HTMLElement = jQuery(inSelector).get(0);
 
-    inBuyerTypes.forEach(arr => {
-        if (!arr[0])
-            return;
-
-        let opt = document.createElement('option');
-        opt.value = arr[0];
-        opt.innerHTML = `${arr[2]} €${arr[1]}`;
-        dropdownBuyerTypes.appendChild(opt);
+    inBuyerTypes.forEach(arr => {        
+        if (arr[0])
+            appendOption(dropdownBuyerTypes, arr)
     });
 }
 
+function appendOption(inDropdownBuyerTypes: HTMLElement, inArr: buyerTypeArr) {
+    let opt: HTMLOptionElement = document.createElement('option');
+    opt.value = <string>inArr[0];
+    opt.innerHTML = `${inArr[2]} €${inArr[1]}`;
+    inDropdownBuyerTypes.appendChild(opt);
+}
+
 function getBuyerTypesByPricescaleID(inPricescaleID: string) {
-    const venueXML = config.state.inVenueXML!;
-    const venuePricescaleArr = venueXML.price_structure[0].pricescale;
+    const venueXML: I.VenueXML = config.state.inVenueXML!;
+    const venuePricescaleArr: I.Pricescale5[] = venueXML.price_structure[0].pricescale;
+    
     const buyerTypesArr = venuePricescaleArr.find(obj => {
         return obj.id[0] === inPricescaleID;
     })?.buyer_type;
@@ -59,7 +65,7 @@ function getBuyerTypesByPricescaleID(inPricescaleID: string) {
     if (!buyerTypesArr)
         return;
 
-    const buyerTypes: (string | undefined)[][] = buyerTypesArr.map(arr => {
+    const buyerTypes: buyerType = buyerTypesArr.map(arr => {
         const buyerTypeDesc = venueXML.venue[0].buyer_types[0].buyer_type.find(obj => {
             return obj.id[0] === arr.id[0] ? obj.desc[0] : undefined;
         })?.desc[0];