Question

我需要确保选择了一位艺术家，但不确定我是否应该使用＆＃34;艺术家＆＃34;或＆＃34;选择＆＃34;。我试过了两个，但它没有用。如果没有选择，代码必须显示警告。

＆＃13;

function validate() {
    
    var select_artist = document.getElementById('artist');
    if (artist == "") {
        alert("You need to choose an artist");
        return false;
}

＆＃13;

<div id="artist">	
     
     <p>Select an Artist:
	
<select name="select">	
	
        <option value="0">Choose Artist</option>
		
		
		<option value="1">Bobby Smith</option>


		<option value="2">The Vibes</option>


        <option value="3">Kids of Rock</option>

</select>

</div>

＆＃13;

Answer 1

您可以使用selectedIndex;

function validate() {

    var select_artist = document.getElementById('artistselect');
    if (select_artist.selectedIndex < 1) {
        alert("You need to choose an artist");
        return false;
    }
}

此外，您正尝试使用div元素获取所选选项。而是设置select元素的id属性。

<select name="select" id = "artistselect">

Answer 2

＆＃13;

function validate() {
   var select_artist = document.getElementById('select');
   if(select_artist.selectedIndex ==  0)
     alert("You need to choose an artist")
}

＆＃13;

<div id="artist">	
     <p>Select an Artist:
<select id="select" onchange="validate()">	
    <option>Choose Artist</option>
	<option >Bobby Smith</option>
    <option>The Vibes</option>
    <option>Kids of Rock</option>
</select>
</div>

＆＃13;

从下拉框中选择

2 个答案: