获取jquery元素值

Question

我试图<select>使用jQuery 基于元素的值做一个简单的条件语句.这很好用:

var WantCategory = document.getElementById('WantCategory').value
if ((WantCategory <= 0) || (WantCategory >= 4)) {
    alert('hi')
}

这不起作用:

var WantCategory =$('select.WantCategory').val()
if ((WantCategory <= 0) || (WantCategory >= 4)) {
    alert('hi')
}

这是html部分

<label for="WantCategory">Item Category
    <select id="WantCategory">
        <optgroup label="Group of Options">
            <option value="0"></option>
            <option value="1">Option 1</option>
            <option value="2">Option 2</option>
            <option value="3">Option 3</option>
        </optgroup>
    </select>
</label>

Answer 1

试试这个:

var WantCategory = $('select#WantCategory').val();
if ((WantCategory <= 0) || (WantCategory >= 4)) {
    alert('hi')
}

您的原始代码是按类而不是按ID进行选择.