Javascript do-while循環問題

我需要在do/while語句循環中循環javascript的幫助。Javascript do-while循環問題

我遇到的問題是，我不想在輸入無效產品時在表格中顯示不正確的信息，但它確實顯示在document.write中。我需要幫助才能確保不會顯示不正確的信息。

此外，當我點擊「確定」添加更多我的訂單，它不會循環它，而只是顯示document.write。如果您點擊「確定」按鈕，我想讓它循環。

謝謝你的幫助。

下面是代碼：

<html> 

    <head><title>Javascript Assignment 3: Daniel Weiner</title> 
     </head> 
    <body bgcolor="brown"> 

    <h1 align="center">Big Ben's Burgers-eCommerce</h1> 

    <table border="1" width="100%" height="450px" bgcolor="gray"><tr> 
     <th align="center">Product/Service</th> 
     <th align="center">Price</th> 
     <th align="center">Discount</th> 
    </tr> 

    <tr bgcolor="orange"> 
     <td align="center"><font size="3">Hamburger 
    <br> 
    <br> 
    <a href="http://www.mcdonalds.com/us/en/food/product_nutrition.sandwiches.256.Hamburger.html" target="_blank">Classic Hamburger</a> 

     <td align="right" bgcolor="orange"><font size="3">$8.00</font></td> 
     <td align="center" bgcolor="orange"><font size="3">.10</font></td> 
    </tr> 

    <tr bgcolor="orange"> 
     <td align="center"><font size="3">Cheeseburger 
    <br> 
    <br> 
    <a href="http://www.mcdonalds.com/us/en/food/product_nutrition.sandwiches.284.cheeseburger.html" target="_blank">Classic Cheeseburger </a> 
    </font></td> 
     <td align="right" bgcolor="orange"><font size="3">$9.00</font></td> 
     <td align="center" bgcolor="orange"><font size="3">.05</font></td> 
    </tr> 

    <tr bgcolor="orange"> 
     <td align="center"><font size="3">Soda 
    <br> 
    <br> 
    <a href="http://www.mcdonalds.com/us/en/food/full_menu/beverages.html" target="_blank">Fabulous Drinks</a> 
    </font></td> 
     <td align="right" bgcolor="orange"><font size="3">$2.00 
    </font></td> 
    <td align="center" bgcolor="orange"><font size="3"> .07</font></td> 
    </tr> 

    <tr bgcolor="red"> 
     <td align="center"><font size="3"> French Fries 
    <br> 
    <br> 
    <a href="http://www.mcdonalds.com/us/en/food/product_nutrition.snackssides.120.small-french-fries.html" target="_blank"> Fries</a> 
    </font></td> 
     <td align="right" bgcolor="red"><font size="3"> $4.00</font></td> 
     <td align="center" bgcolor="red"><font size="3">.15</font></td> 

    </table> 
    <script type="text/javascript"> 
    /*Daniel Weiner, Fengpeng Yuan, Javascript 2, Nov 4,2011*/ 

    var username; 
    var bprice= 8; 
    var chprice= 9; 
    var sprice= 2; 
    var fprice= 4; 
    var price= 0; 
    var a; 
    var b; 
    var product= "hamburger, cheeseburger, soda, fries"; 
    var quantity =0; 
    var total; 
    var cost = 0; 
    var discount= 0; 
    do{ 
    username =prompt("Welcome to Big Ben's Burgers. Please enter your name.", ""); 
    alert("Hello " + username+". Please look through our available products and services before placing your order.",""); 
    product=prompt("What do you want?",""); 

    quantity =1*prompt("How many of " +product+ " would you like?"); 




    if (product == "hamburger") 
    { 
    price = bprice; 

    discount = .1; 
    } 
    else if (product == "cheeseburger") 
    { 
    price = chprice; 

    discount = .05; 
    } 

    else if (product == "soda") 
    { 
    price = sprice; 

    discount = .07; 
    } 

    else if (product == "fries") 
    { 
    price = fprice; 

    discount = .15; 
    } 

    else{ 
     alert("Sorry, " +username+ " Your item not found."); 
    } 
     cost=price*quantity 
     discount=price*discount*quantity 
     total=cost-discount 
    document.write("The cost of buying " +quantity+ " of " +product+ " is $" +cost+ ".<br/>"); 
    document.write("This discount for this purchase is $" +discount+ ".<br/>"); 

    }while(a==false) 
    a = confirm("Do you want to place another order?"); 

    (b==false) 
    document.write("Thank you for placing an order with us, " +username+ ".<br/>"); 
    document.write("The total order cost is $" +total+ "."); 

    </script> 
    </body> 
    </html>

來源

2011-11-03 djw32592

我重新標記這是[標籤：JavaScript的] - Java和Javascript有一樣共同作爲一輛汽車和一個胡蘿蔔。例如， – corsiKa

+1。 – denolk

對於問題的第二部分，你必須在循環波紋管使用語句

a = confirm("Do you want to place another order?");

來源

2011-11-03 20:43:45 denolk

我在哪裏把a = confirm（「你想要下另一個訂單？」）;如果你想要求確認，那麼我是否會做另一個如果陳述，或者我把它放在else語句 – djw32592

，該陳述應該在循環中。在你的情況下，do {}語句結束之前，關閉它。 – denolk

看起來你是不是調理輸出是否選擇有效產品的結果的部分。你需要像下面這樣的東西;

do{ 
    .... 

    productValid = false; 

    if (product == "hamburger") 
    { 
    price = bprice; 

    discount = .1; 
    productValid = true; 

    } 
    else if (product == "cheeseburger") 
    { 
    price = chprice; 

    discount = .05; 
productValid = true; 

    } 

    else if (product == "soda") 
    { 
    price = sprice; 

    discount = .07; 
productValid = true; 
    } 

    else if (product == "fries") 
    { 
    price = fprice; 

    discount = .15; 
productValid = true; 
    } 

    else{ 
     alert("Sorry, " +username+ " Your item not found."); 
    } 

if(productValid){ 
     cost=price*quantity 
     discount=price*discount*quantity 
     total=cost-discount 
    document.write("The cost of buying " +quantity+ " of " +product+ " is $" +cost+ ".<br/>"); 
    document.write("This discount for this purchase is $" +discount+ ".<br/>"); 
} 
else 
{ 
    document.write("No valid product selected<br>"); 
} 
a = confirm("Do you want to place another order?"); 

    }while(a==true)

來源

2011-11-03 20:51:20 Bryan

另外，正如其他人所說的那樣，用於放置另一個訂單的confirm（）應該發生在do-while內部，並且檢查的條件會是while（a == true），因爲如果它們需要再次循環選擇是。 – Bryan

提示：用'productValid = true;'開始你的循環，如果找不到*，則將其更改爲false。這樣你就不用多次寫了。 –

同意，但你可以在那一方面爭論。我通常更喜歡我最初的方法，因爲閱讀代碼時更有意義（產品在明確檢查之前無效），但需要花費額外的代碼。 – Bryan

如果用戶點擊cancel，那麼您正在重新循環該循環。更改while(a==false)到while(a==true)或者乾脆while(a)

也把線

a = confirm("Do you want to place another order?");

在你的循環中的最後一行，而不是以後就行了。

你可以設置一個標誌，無功，讓你知道如果該項目被發現沒有，並檢查它在你的循環結束，以避免不存在的項目顯示數據：

<script type="text/javascript"> /*Daniel Weiner, Fengpeng Yuan, Javascript 2, Nov 4,2011*/ var username; var bprice= 8; var chprice= 9; var sprice= 2; var fprice= 4; var price= 0; var a; var b; var product= "hamburger, cheeseburger, soda, fries"; var quantity =0; var total; var cost = 0; var discount= 0; var flag; do{ flag = true; //assume found unless otherwise username =prompt("Welcome to Big Ben's Burgers. Please enter your name.", ""); alert("Hello " + username+". Please look through our available products and services before placing your order.",""); product=prompt("What do you want?",""); quantity =1*prompt("How many of " +product+ " would you like?"); if (product == "hamburger") { price = bprice; discount = .1; } else if (product == "cheeseburger") { price = chprice; discount = .05; } else if (product == "soda") { price = sprice; discount = .07; } else if (product == "fries") { price = fprice; discount = .15; } else{ alert("Sorry, " +username+ " Your item not found."); flag = false; } if(flag){ cost=price*quantity discount=price*discount*quantity total=cost-discount document.write("The cost of buying " +quantity+ " of " +product+ " is $" +cost+ ".<br/>"); document.write("This discount for this purchase is $" +discount+ ".<br/>"); } a = confirm("Do you want to place another order?"); }while(a); alert('goodbye'); </script>

來源

2011-11-03 20:52:47

Javascript do-while循環問題

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