If the two pages are on the same domain, a third way is to use HTML5 localStorage: http://diveintohtml5.info/storage.html

In fact localStorage is precisely intended for what you want. Dealing with GET params or window/document JS references is not very portable (even if, I know, all browsers do not support localStorage).

Assuming your server supports PHP, you could also use a PHP Session.

http://www.php.net/manual/en/reserved.variables.session.php

If this is your real server side code then...its completely insecure. You should never pass variables posted by users directly into your queries.

$query2 = "insert into booking(cust_email, cust_mobile, cust_name) values('$mail','$mobile','$name')";  

At least escape the values using "mysql_real_escape_string", or use prepared statements. And...dont use mysql anymore, use mysqli, which is almost identical to what you are using, but not deprecated soon.

Also, you are json encoding a string that doesnt need to be json encoded, its just a piece of text and not valid json code. This may be why @SimarjeetSingh Panghlia answer doesnt work for you.

instead of json_encoding that value, encode a structured array.

$response = array( "status" => true );

if(isset($_POST['type']))
    {
        if($_POST['type']=="booking"){
            $name = mysql_real_escape_string( $_POST ['Name'] ));    
            $mobile = mysql_real_escape_string($_POST ['Mob_Num']);
            $mail = mysql_real_escape_string($_POST ['Email']);               
            $query1 = "insert into customer(userName, userContactNumber, email) values('$name','$mobile','$mail')";
            $query2 = "insert into booking(cust_email, cust_mobile, cust_name) values('$mail','$mobile','$name')";          

            $result1 = mysql_query($query1);          
            $result2 = mysql_query($query2);
            $id = mysql_insert_id();

            $response["message"] = "Welcome Mr/Mrs ".$name."  Thanks for booking home services your booking id is =  ".$id;/* make sure you strip tags etc to prevent xss attack */

        }
    }
    else{
        $response["status"] = false;
        $response["message"] = "Invalid format";
    }

    echo json_encode($response);

    /* Note that you are making the query using ContentType:"application/json", */

which means you should respond using json regardless if query is successful or not. I would also recommend using a simple jQuery plugin called jStorage, that allows easy get/set of objects without having to serialize them.

You can dynamically create a hidden form with inputs containing your data inside, and submit it to desired address

Example using jQuery:

var url = 'index.html';
var data = {
  a: 1,
  b: { a: 1, b: 2},
  c: [1, 2, 3]
};

function appendData($form, prefix, data) {
  function append(k, data) {
    if (prefix !== '') {
      appendData($form, prefix + '[' + k + ']', data[k]);
    } else {
      appendData($form, k, data[k]);
    }
  }
  if (data instanceof Object) {
    if ($.isArray(data)) {
      for (var i = 0, l = data.length; i < l; i++) {
        append(i, data);
      }
    } else {
      for (var k in data) {
        append(k, data);
      }
    }
  } else {
    var inp = $('<input type="hidden" name="' + prefix + '">').val(data);
    $form.append(inp);
  }
}
var $form = $('<form style="display:none;" action="' + url + '" method="post"/>');

appendData($form, '', data);
$('body').append($form);
$form[0].submit();

http://plnkr.co/edit/bM4oAj7TZNWfjkLVWMrY

In your BookScreen, change it to the following:

export default function BookScreen({ navigation, route }) {
  const { item } = route.params;

  return (
    <View style={styles.container}>
      <Text style={styles.text}>{item.name}</Text>
    </View>
  );
}

Edit: I think you should pass the data like this:

navigation.navigate('Book', {item: item});

EDIT

var options = {foo:'foo'};
var myURL="http://localhost";
window.open( myURL + "/?options=" + JSON.stringify(options) );

didn't test that code before, try this, you can access it through GET