動態表單字段隨javascript變化

Question

Hy！我對網絡開發不熟悉，只是停留在某一點上。我有一個表單，其中2個字段由一個下拉菜單生成。現在的問題是我已經產生了一個領域，並試圖獲得另一個領域，但由於缺乏知識我卡住了。我只是需要一點幫助，如果有人能

<form name="myform"> 
    <select name="optone" size="1" onchange="setOptions(document.myform.optone.options[document.myform.optone.selectedIndex].value);"> 
     <option value=" " selected="selected"> </option> 
     <option value="1">Directory Submission</option> 
     <option value="2">Articale Submission</option> 
     <option value="3">Social Bookmarking</option> 
     <option value="4">Blog Commenting</option> 
     <option value="5">Forum Submission</option> 
     <option value="6">Link Building</option> 
    </select> 
    No. Of Submissions: <select name="opttwo" size="1"> 
     <option value=" " selected="selected">Select any option of the above first</option> 
    </select> 
    Amount Payable: 
</td> 
<td> 
    <input type="text" name="amount" onchange="document.myform.opttwo.options[document.myform.opttwo.selectedIndex].value;" /> 

現在我的JavaScript是這樣的：

function setOptions(chosen) { 
    var selbox = document.myform.opttwo; 
    selbox.options.length = 0; 
    if (chosen == " ") { 
     selbox.options[selbox.options.length] = new Option('Please select one of the options above first',' '); 
    } 
    if (chosen == "1") { 
     selbox.options[selbox.options.length] = new Option('100 Directory Submission', '$9.99'); 
     selbox.options[selbox.options.length] = new Option('100 Directory Submission', '$9.99'); 
     selbox.options[selbox.options.length] = new Option('300 Directory Submission','$29.99'); 
    } 

    // and like this other options will come too. 
} 

我只是想知道，怎麼個場量的支付將獲得的金額。

Answer 1

你的意思

DEMO

function setOptions(chosen) { 
    var selbox = document.myform.opttwo; 
    selbox.options.length = 1; // no need to delete the first option 
    if (chosen == "1") { 
        selbox.options[selbox.options.length] = new Option('100 Directory Submission', '$9.99'); 
        selbox.options[selbox.options.length] = new Option('100 Directory Submission', '$9.99'); 
        selbox.options[selbox.options.length] = new Option('300 Directory Submission','$29.99'); 
    } 
    document.myform.amount.value=""; 
    // and like this other options will come too. 
}​ 

與此代碼

 <select name="opttwo" size="1" onchange="this.form.amount.value=this.value;"> 
     <option value=" " selected="selected">Select any option of the above first</option> 
     </select> 
     Amount Payable: 
    </td> 
    <td> 
    <input type="text" name="amount" readonly="readonly" />