输入后立即获取Checkbox值并将其放入PHP变量中

Question

PHP新手！我有这个表格。它包含三个下拉菜单。第一个菜单有SQL查询的选项。另外两个只是HTML。我们也在使用Bootstrap Multiselect，因此在屏幕上显示为3个下拉菜单，其中包含复选框。我们还有一个提交按钮，显示已选中的复选框。这是我的代码：

<form id="numberOrderForm" method="POST">
    <div class="wrappers" id="multi-select1Wrapper">
        <h2>Area Code</h2>
        <select class="dropDownMenus" id="multi-select1" name="multi_select1[]" multiple="multiple" action="index.php">
            <?php
                //The query asking from our database
                $areaCodeSQL = "SELECT ac.Number AS `AreaCode`, ac.Name AS `AreaName`
                                FROM `AreaCodes` ac";                                                               //SQL query: From the table 'AreaCodes' select 'Number' and put into 'AreaCode', select Name and put into 'AreaName'

                $areaCodeResults = $conn->query($areaCodeSQL);                                                      // put results of SQL query into this variable

                if ($areaCodeResults->num_rows > 0) {                                                               // if num_rows(from $results) is greater than 0, then do this:
                    // output data of each row
                                foreach($areaCodeResults as $areaCodeResult)                                        //for each item in $areCodeResults do this:
                                    {
                                        $areaNameAndCode =  $areaCodeResult['AreaCode'] ." ". $areaCodeResult['AreaName'];  //get AreaCode and AreaName from query result and concat them
                                        $areaName = $areaCodeResult['AreaName'];                                    // get AreaName
                                        $areaCode = $areaCodeResult['AreaCode'];                                    //get AreaCode

                                        ?><option class="menuoption1" name="menuAreaCode" value="<?php echo $areaCode ?>"  ><?php echo $areaNameAndCode; ?></option><?php  //Create this option element populated with query result variables
                                    }
                } 

            ?>
        </select>
    </div>       

    <div class="wrappers" id="multi-select2Wrapper">
        <h2>Number Type</h2>
        <select class="dropDownMenus" id="multi-select2" name="multi_select2[]" multiple="multiple" action="index.php">
            <option class="menuoption2" value="gold">Gold</option>
            <option class="menuoption2" value="silver">Silver</option>
            <option class="menuoption2" value="bronze">Bronze</option>
        </select>
    </div>

    <div class="wrappers" id="multi-select3Wrapper">
        <h2>Order</h2>
        <select class="dropDownMenus" id="multi-select3" name="multi_select3[]" action="index.php">
            <option class="menuoption3" value="sequential">Sequential</option>
            <option class="menuoption3" value="random">Random</option>
        </select>
    </div>

    <div id="submitButtonWrapper" class="dropDownMenus">
        <button id="submit" class="btn">submit</button>
    </div>
</form> 

<div id="showResults1"><!--test div to show contents of $_POST['multi-select1'] -->
    <?php 
        $areaCode = isset($_POST['multi_select1']) ? $_POST['multi_select1'] : []; // This is an if/else statement written in shorthand
        var_dump($areaCode) 
    ?>
</div> 

<div id="showResults2"><!--test div to show contents of $_POST['multi-select2'] -->
    <?php 
        $numberType = isset($_POST['multi_select2']) ? $_POST['multi_select2'] : []; // This is an if/else statement written in shorthand
        var_dump($numberType) 
    ?>
</div> 

<div id="showResults2"><!--test div to show contents of $_POST['multi-select3'] -->
    <?php 
        $order = isset($_POST['multi_select3']) ? $_POST['multi_select3'] : []; // This is an if/else statement written in shorthand
        var_dump($order) 
    ?>
</div> 

但是现在我希望在没有<submit>按钮的情况下获得类似的结果。我仍然希望用户检查过什么，但是在检查到下面的<div>元素中时会立即显示它。我还必须只使用PHP并在最后将这些值放在PHP变量中。有什么想法吗？