如何使用jquery [duplicate]访问php变量

hi i want to get the this php variable by jquery and use it for ajax this my php code and i use it in php page

function product($li)
{
    $result = mysqli_query($li, "SELECT * FROM product ORDER BY id ASC") or die(mysqli_error($li));

    while ($Row = mysqli_fetch_array($result)) {
        echo "<div class='product'>";

        echo "<img src=" . $Row['imageurl'] . " width='100' height='75'>";
        echo $Row['farsiname'];
        echo $Row['englishname'];
        echo $Row['description'];
        echo $Row['price'];
            echo getid($li , $Row['id']);
           echo '<button class="add_to_cart">برو تو سبد</button>';
        echo '<input type="hidden" class="id" name="productid" value="' . $Row['id'] . '" />';

        echo '</div>';
    }
}

i want to get $row['id'] by jquery when i click button please help me!

</div>

$('.add_to_cart').on('click',function(){
  alert($(this).closest('.product').find('.id').val())
})

The main approach for this case is to render Javascript code with PHP.

Below there is a pseudocode showing the approach:

<script language="Javascript">
 var id = <?php echo $Row['id']; ?>;
</script>

You want to get it's value from the hidden input field, right?

If so, then you simply need to do this in jQuery.

$(".id").val();

This is finding the value of the hidden input field with the class of id.

If your id is an integer:

echo '<script> var id = ' . $Row['id'] . '; </script>';

else:

echo '<script> var id = "' . $Row['id'] . '"; </script>';

Rewrite your code by follow my steps

function product($li)
{
    $result = mysqli_query($li, "SELECT * FROM product ORDER BY id ASC") or die(mysqli_error($li));

    while ($Row = mysqli_fetch_array($result)) {
        echo "<div class='product'>";

        echo "<img src=" . $Row['imageurl'] . " width='100' height='75'>";
        echo $Row['farsiname'];
        echo $Row['englishname'];
        echo $Row['description'];
        echo $Row['price'];
            echo getid($li , $Row['id']);
           echo '<button class="add_to_cart" data-datac="'.$Row['id']'.">برو تو سبد</button>';
        echo '</div>';
    }
}

//Jquery

$('.add_to_cart').click(function() {
        var d = $(this).data('datac');      
        alert(d);   
} );