检查是否有未选择的DropDownList

Question

假设有3个下拉列表，如何检查是否有未选择的下拉列表？

var unselected = $('.dropdown:selected').lenght;

if(unselected > 0){
alert('At least one dd is not selected')
}

Answer 1

如果我理解正确，那么您想检查一下是否有一些下拉列表没有被选中，只有一个被禁用的选项。

您可以执行以下操作：

 function checkSelected(){ $('select').each(function(){ console.log($('option',this).not(':disabled').is(':selected') ? 'selected' : 'no selection for ' + $(this).attr('id') ) }) } 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select id="select1"> <option disabled selected value> -- Please select -- </option> <option value="1">A Test 1</option> <option value="2">A Test 2</option> </select> <select id="select2"> <option disabled selected value> -- Please select -- </option> <option value="1">B Test 1</option> <option value="2">B Test 2</option> </select> <select id="select3"> <option disabled selected value> -- Please select -- </option> <option value="1">C Test 1</option> <option value="2">C Test 2</option> </select> <button onclick="checkSelected()">Click me!</button> 

Answer 2

@Sphinx的修改代码。 显示“未选定”下拉列表和“总计”下拉列表的计数。

 function checkSelected(){ var i = 0; var total = $('.dropdown').length; $('.dropdown').each(function(){ //console.log($(this).attr('id')); if(!$('option',this).not(':disabled').is(':selected')) i++; // console.log(i + " dropdowns are NOT selected"); }); console.log(i + " of " + total +" dropdowns are NOT selected"); } 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select id="select1" class="dropdown"> <option disabled selected value> -- Please select -- </option> <option value="1">A Test 1</option> <option value="2">A Test 2</option> </select> <select id="select2" class="dropdown"> <option disabled selected value> -- Please select -- </option> <option value="1">B Test 1</option> <option value="2">B Test 2</option> </select> <select id="select3" class="dropdown"> <option disabled selected value> -- Please select -- </option> <option value="1">C Test 1</option> <option value="2">C Test 2</option> </select> <button onclick="checkSelected()">Click me!</button>