如果在使用JavaScript的下拉列表中的功能

Question

我想製作一個專家系統來檢測網絡問題。用戶將有4個問題，每個問題有3到4個答案。在用戶輸入之後，用戶將點擊按鈕，它將檢測並解決問題。我有點想法，但我知道有幾件事情不見了。目前，我只添加了2個隨機問題和答案，以檢查是否實際工作。請幫助使用java腳本，因此它會根據答案給出有關網絡問題的詳細信息。提前致謝！ :)

1.Can you access to the internet? <BR> 

<select id="internet"> 

    <option value="yes">yes</option> 

    <option value="No">no</option> 

    <option value="Yes, but at slow">Yes, but at slow</option> 

    <option value="Yes/No, it workes but it suddenly it stops and start working again ">Yes/No, it workes but it suddenly it stops and start working again</option> 

</select> 

<br> 

<br><p> 


2.Is it just your computer?<BR> 



<select id="computer"> 

    <option value="yes">yes</option> 

    <option value="whole company">whole company</option> 

    <option value="just my department">just my department</option> 

    <option value="me and few staff">me and few staff</option> 

</select> 

<br> 

<br><p> 




<button onclick="myFunction()">Detect</button> 

<p id="Solution"></p> 

<script> 
function myFunction() 
{ 

if (internet=="no"||computer=="yes") 
  { 
  x="check your cable is not cut or loose"; 
  } 
else if (internet=="no"||computer=="yes") 
  { 
  x="connection problem"; 
  } 
else 
  { 
  x="other problems...."; 
  } 
document.getElementById("Solution").innerHTML=x; 
} 
</script> 

Answer 1

function myFunction() 
{ 
    var internetElem = document.getElementById("internet"); 
    var internet = internetElem.options[internetElem.selectedIndex].value; 
    var computerElem = document.getElementById("computer"); 
    var computer= internetElem.options[internetElem.selectedIndex].value; 

    if (internet=="no"||computer=="yes") { 
     x="check your cable is not cut or loose"; 
    } else if (internet=="no"||computer=="yes") { 
     x="connection problem"; 
    } else { 
     x="other problems...."; 
    } 
    document.getElementById("Solution").innerHTML=x; 
} 

你需要這樣的東西上面。只需通過它的id找到一個元素，獲取所選元素的索引並獲取所選選項的值。請注意，值將返回你所放置在<option value="..."和字符串比較是大小寫敏感的，所以internet == "no"，將無法正常工作，你應該將其更改爲internet == "No"（或更改HTML標記的值）