Get value of multiselect box using jQuery or pure JS

问题

In the code shown below, how to get the values of multiselect box in function val() using jQuery or pure JavaScript?

<script>
    function val() {
        //Get values of mutliselect drop down box
    }

    $(document).ready(function () {
        var flag = 0;
        $('#emp').change(function () {
            var sub = $("OPTION:selected", this).val()
            if (flag == 1) $('#new_row').remove();
            $('#topics').val('');
            var html = '<tr id="new_row" class="new_row"><td>Topics:</td><td>  <select    id="topic_l" name="topic_l" class="topic_l" multiple="multiple">';
            var idarr = new Array();
            var valarr = new Array(); { %
                for top in dict.tops %
            }
            idarr.push('{{top.is}}');
            valarr.push('{{pic.ele}}'); { % endfor %
            }
            for (var i = 0; i < idarr.length; i++) {
                if (sub == idarr[i]) {
                    html += '<option value="' + idarr[i] + '" >' + valarr[i] + '</option>';
                }
            }
            html += '</select></p></td></tr>';
            $('#tops').append(html);
            flag = 1;
        });
    });
</script>
Emp:&nbsp;&nbsp;&nbsp;&nbsp;
<select id="emp" name="emp">
    <option value=""></option>
    <option value="1">1</option>
</select>

<div name="tops" id="tops"></div>

<input type="submit" value="Create Template" id="create" onclick="javascript:var ret=val();return ret;">

回答1:

the val function called from the select will return an array if its a multiple. $('select#my_multiselect').val() will return an array of the values for the selected options - you dont need to loop through and get them yourself.

回答2:

I think the answer may be easier to understand like this:

$('#empid').on('change',function() {
  alert($(this).val());
  console.log($(this).val());
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.0/jquery.min.js"></script>
<select id="empid" name="empname" multiple="multiple">
  <option value="0">Potato</option>
  <option value="1">Carrot</option>
  <option value="2">Apple</option>
  <option value="3">Raisins</option>
  <option value="4">Peanut</option>
</select>
<br />
Hold CTRL / CMD for selecting multiple fields

If you select "Carrot" and "Raisins" in the list, the output will be "1,3".

回答3:

var data=[];
var $el=$("#my-select");
$el.find('option:selected').each(function(){
    data.push({value:$(this).val(),text:$(this).text()});
});
console.log(data)

回答4:

According to the widget's page, it should be:

var myDropDownListValues = $("#myDropDownList").multiselect("getChecked").map(function()
{
    return this.value;    
}).get();

It works for me :)

回答5:

This got me the value and text of the selected options for the jQuery multiselect.js plugin:

$("#selectBox").multiSelect({
    afterSelect: function(){
        var selections = [];
        $("#selectBox option:selected").each(function(){
            var optionValue = $(this).val();
            var optionText = $(this).text();
            console.log("optionText",optionText);                
            // collect all values
            selections.push(optionValue);
        });

        // use array "selections" here.. 
    }
});   

very usefull if you need it for your "onChange" event ;)

回答6:

You could do like this too.

<form action="ResultsDulith.php" id="intermediate" name="inputMachine[]" multiple="multiple" method="post">
    <select id="selectDuration" name="selectDuration[]" multiple="multiple"> 
        <option value="1 WEEK" >Last 1 Week</option>
        <option value="2 WEEK" >Last 2 Week </option>
        <option value="3 WEEK" >Last 3 Week</option>
         <option value="4 WEEK" >Last 4 Week</option>
          <option value="5 WEEK" >Last 5 Week</option>
           <option value="6 WEEK" >Last 6 Week</option>
    </select>
     <input type="submit"/> 
</form>

Then take the multiple selection from following PHP code below. It print the selected multiple values accordingly.

$shift=$_POST['selectDuration'];

print_r($shift);

来源：https://stackoverflow.com/questions/2543322/get-value-of-multiselect-box-using-jquery-or-pure-js