如何在使用PHP访问的JavaScript中存储MySQL数据库值

Question

I have accessed MySQL database values containing product_name, price, and id to php variable using PHP code. Now I want that variable holding MySQL data to save in Java Script variable so that I can perform some function.

Here is the code:

this is a php file:

<?php include("connect.php");

 $plan = mysql_query("select id,price,product_name from product"); 
 <select name='pro2' id='pro2' >\\dropdown menu for selecting product name
 <option>Select product</option>
 <?php while($proname2 = mysql_fetch_array($plan))
 { ?> 
 <option value="<?php echo $proname2['product_name']; ?>" >
 <?php echo$proname2['product_name']; ?> </option>
<?php } ?>  
 </select>
 Unit Price:<input type="text" id="mytext1" name="mytext1" readonly="enabled" value=""/>

<?php 
   $plan = mysql_query("select price,product_name from product");
   while($row = mysql_fetch_array($plan))
  {  $r1=$row['product_name'];
     $r2=$row['price'];
      $user_data = array('product_nam' => '$r1', 'price' => '$r2'); 
?>
<script type="text/javascript">\\ used java script to change the value of mytext to  \\price which is selected by product name 
    alert(user_data.price);
    var mytextbox2 = document.getElementById('mytext1');
    var mydropdown2 = document.getElementById('pro2');
    var user_data = <?php echo json_encode($user_data); ?>; 
    mydropdown2.onchange = function(){
         // test.value =this.value;
        if(user_data.product_nam==this.value)
        {            
            mytextbox2.value=user_data.price;
        }
      //to appened
         //mytextbox.innerHTML = this.value;
    }
</script>
    <?php } ?>

Answer 1

For a fresh page load (not AJAX), as the PHP code will execute before the data is sent to the user, you can echo the PHP variable value directly into the Javascript variable declaration.

For instance, try:

        <script>
            $(document).ready(function() {
                var echome = <?php echo "1";?>;
                console.log(echome);
            }); 
        </script>

Additionally, you should avoid using mysql_~ function calls. They are deprecated. You should considering upgrading to mysqli or PDO.