function storeData(item){
    $.ajax({
        url: 'insert.php',
        type: 'POST',
        data: {
            var1: item
        }
    });
}

<?php
    $host = "localhost:3306";
    $user = "root";
    $pass = "";
    $databaseName = "items";
    $tableName = "item_list";

    $con = mysql_connect($host,$user,$pass);
    $dbs = mysql_select_db($databaseName, $con);
?>

<?php
    include_once('connection.php');

    $itemNumber = $_POST['var1'];
    echo $_POST[$itemNumber];
    $sql = "INSERT INTO item_list (item_number) VALUES ($itemNumber)";
    mysql_query($sql) or die(mysql_error());
?>