Javascript变量问题

Question

你好，我正试图让这个程序添加整个循环中累积的所有总成本。但该计划不断打印最新的成本，而不是所有“已购买”的产品。这里是我的代码：`

 var Customer_Name, Discount, Product="", Price, Quantity="", Cost ; 
     var blanket_price = 25; 
     var lotion_price = 60; 
     var surfboard_price = 60; 
     var sunscreen_price = 60; 
     var Customer_Name = prompt("Welcome to Jersey Shore Inc.! What is your name?","Type Name Here"); 
     alert("Hello "+Customer_Name+", Please look through all available products and services before placing your order."); 


    do 
    { 


    Product= prompt("What product would you like?","Type Product Name Here"); 
    Quantity= prompt("How much of the "+Product+" would you like?","Type Quantity Here"); 
    var Total_Cost; 
    var SumOrderTotal=0; 

     if (Product == "blanket") 
      { 
       alert("You received a 50% discount! Click okay to see your receipt below."); 
       Total_Cost= 0.5*(Quantity*blanket_price); 
       Cost=(Quantity*blanket_price); 
       Discount = .50*blanket_price; 
      } 
      else if (Product == "lotion") 
      { 
       alert("You received a 50% discount! Click okay to see your receipt below."); 
       Total_Cost= 0.5*(Quantity*lotion_price); 
       Cost=(Quantity*lotion_price); 
       Discount = .50*lotion_price; 
      } 
      else if (Product == "surfboard") 
      { 
       alert("You received a 50% discount!Click okay to see your receipt below."); 
       Total_Cost= 0.5*(Quantity*surfboard_price); 
       Cost=(Quantity*surfboard_price); 
       Discount = .50*surfboard_price; 

      } 
      else if (Product == "sunscreen") 
      { 
       alert("You received a 50% discount! Click okay to see your receipt below."); 
       Total_Cost= 0.5*(Quantity*sunscreen_price); 
       Cost=(Quantity*sunscreen_price); 
       Discount = .50*sunscreen_price; 

      } 

      if((Product=="blanket" || Product=="sunscreen" || Product=="lotion" || Product=="surfboard")) 
      { 

       document.write("The cost of buying " + Quantity+ " of " + Product + " is $ "+ Cost +". </br>"); 
       document.write("The discount for this purchase is $ "+Total_Cost+". <br/>"); 



      } 
      else 
      { 
       alert("Sorry "+Customer_Name+" you entered an invalid product.(Refer to table for our products) Please Refresh the page to reload and place a new order."); 

      } 
    var SumOrderTotal = Total_Cost + SumOrderTotal; 
    var user_answer=confirm("Would you like to continue purchasing products?"); 

    } 
    while(user_answer==true); 

       document.write("Thank you for placing an order with us, " +Customer_Name+". <br/>"); 
       document.write("Your total order cost is $"+ SumOrderTotal+ ". <br/>"); 

`

Answer 1

移动SumOrderTotal以外的做......而。

像这样：

var SumOrderTotal=0; 
    do {  
    Product = prompt("..."); 
    Quantity = prompt("..."); 
    var Total_Cost; 
    } while (...) { 
    ... 
    } 

因为你每次都初始化为0，在启动周期（do..while）。