Jquery 按值更改所选选项

Question

如何按值更改所选选项？加载时选择对象 默认选择一个对象，我想按值设置它。

<select id="county">
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>

var $county_id = $('#county_id');
    var $city_id = $('#city_id').val();

    var $selected_county = $('#selectedCounty').val();



    $county_id.html('');

    $.get('/base/get_city_counties',{city_id:$city_id},function(res){
        res = eval('('+res+')');
        var len = res.length,i,$option = $('<option>'),$option_;
        for(i=0;i<len;i++)
        {
            $option_ = $option.clone(true).val(res[i][0]).html(res[i][1]);
            $county_id.append($option_);
        }
    });

    $('#county option[value=2]').attr('selected','selected');

修复了代码，感谢您的帮助。放置位置错误，我已修复。

$( document ).ready( function() {
    var $county_id = $('#county_id');
    var $city_id = $('#city_id').val();
    var $selected_county = $('#selectedCounty').val();
    $county_id.html('');
    $.get('/base/get_city_counties',{city_id:$city_id},function(res){
        res = eval('('+res+')');
        var len = res.length,i,$option = $('<option>'),$option_;
        for(i=0;i<len;i++)
        {
            $option_ = $option.clone(true).val(res[i][0]).html(res[i][1]);
            $county_id.append($option_);
        }
        $('#county_id').val($selected_county);
    });
    $( 'textarea#jobdesc' ).ckeditor();
} );

Answer 1

您只需将要设置的值作为参数传递到 jQuery 的 val() 方法中即可:

$('#county').val('2');

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<select id="county">
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>