javascript - 控制选择表单中的默认选择

Question

我希望当页面加载时，如果$a=x，则选项1出现在选择表单中，否则如果$a=y，选项2出现在选择表单中，否则应该出现选择。我怎样才能实现这一点？

下面的所有代码都在表格的每一行中，行数未知。

PHP:

 $a;
    echo "<div class='res'> State:";
            if ($a[0]!="") $a=x;
            else if ($b[0]!="") $a=y;
            else echo "None";

echo "<form class='form-horizontal'>
    <fieldset  >   
        <span class='control-group' >
        <span  class='controls'>
            <select id='fl' class='form-control' style='cursor:pointer;'>
                <option selected='selected' style='display:none;' value='0'>Select</option>
                <option value='1'>Option1</option>
               <option value='2'>Option2</option>
               </select>

        </span>
        </span>
        <div><button id='mybtn' type='button'>Save</button></div>
    </fieldset>

</form>";

echo "</div";

Answer 1

switch($a) {
case 'x':
    $default = 1;
    break;
case 'y':
    $default = 2;
    break;
default:
    $default = 0;
}

echo "<form class='form-horizontal'>
    <fieldset  >   
        <span class='control-group' >
        <span  class='controls'>
            <select id='fl' class='form-control' style='cursor:pointer;'>
                <option " . ($default == 0 ? "selected='selected'" : "") . " style='display:none;' value='0'>Select</option>
                <option " . ($default == 1 ? "selected='selected'" : "") . " value='1'>Option1</option>
                <option " . ($default == 2 ? "selected='selected'" : "") . " value='2'>Option2</option>
            </select>

        </span>
    </span>
    <div><button id='mybtn' type='button'>Save</button></div>
    </fieldset>

</form>";