如何使用 jquery 和 javascript 获取类属性值

Question

I'm trying to get the class of the selected option and use that in a compare statement to find which class it is.

I get an undefined value. The option tag has a class set to it.

Why am I not getting a value back?

Html:

<select name="datagrid_filter" onchange="startFilter();">
    <option>All</option>
    <option disabled="true">Assignment:</option>
    <option disabled="true">Client:</option>
    <option disabled="true">Type:</option>
    <option class="type" value="Activity"> &nbsp Activity</option>
    <option class="type" value="Alert"> &nbsp Alert</option>
    <option class="type" value="Lead"> &nbsp Lead</option>
    <option class="type" value="Notification"> &nbsp Notification</option>
</select>

Javascript:

var cs1 = $("option:selected", this).attr("class");
if(cs1 == 'Type'){
    //do something
}

Answer 1

You should change:

onchange="startFilter();" to onchange="startFilter(this);"

and in startFilter function:

function startFilter(ele){
    var className = $("option:selected", ele).attr("class");
    if(className == 'type'){
        //do something
    }
}

Take note that, the this inside startFilter function refers to the window object, not the element you bind it to.

Answer 2

Why don't you use hasClass jQuery API? It's very good in this case:

if($("option:selected", this).hasClass('type')){
    //do something
}

And make sure this referes to a proper object (as @undefined mentioned)
Or use:

if($("option:selected", "select[name=datagrid_filter]").hasClass('type')){
        //do something
    }

Or:

if($("select[name=datagrid_filter] option:selected").hasClass('type')){
            //do something
 }

Answer 3

Try not to have inline JavaScript

Fiddle Demo

JavaScript

   $(function()
    {
        var handleChange    =   function()
                                {
                                    var $this     = $(this);
                                    var $selected = $this.children(":selected");
                                    var isType    = $selected.hasClass('type');
                                    if(isType)
                                    {
                                        alert('Do Something');                        
                                    }
                                };
        var $datagridFilter =  $('[name=datagrid_filter]')

        $datagridFilter.change(handleChange);

    });

Answer 4

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <select onchange="getval(this);" class="sele"> <option>All</option> <option disabled="true">Assignment:</option> <option disabled="true">Client:</option> <option disabled="true">Type:</option> <option class="type" value="Activity"> &nbsp Activity</option> <option class="type" value="Alert"> &nbsp Alert</option> <option class="type" value="Lead"> &nbsp Lead</option> <option class="type" value="Notification"> &nbsp Notification</option> </select> <script> function getval(sel) { if($('.sele :selected').attr('class')) { console.log($('.sele :selected').attr("class","typ123")); // Your code write here } } </script>