Currency converter PHP echo in pop-up - php

Question

I don't know how I can do popup with result in my currency converter with API http://api.nbp.pl/. This is my code:
<?php
if (isset($_POST['kwota']) && isset($_POST['waluta']) && is_numeric($_POST['kwota']) && is_numeric($_POST['waluta'] )){
switch ($_POST['waluta']) {
case 1:
$przelicznik = json_decode(file_get_contents('http://api.nbp.pl/api/exchangerates/rates/a/usd/'))->rates[0]->mid;
break;
case 2:
$przelicznik = json_decode(file_get_contents('http://api.nbp.pl/api/exchangerates/rates/a/eur/'))->rates[0]->mid;
break;
case 3:
$przelicznik = json_decode(file_get_contents('http://api.nbp.pl/api/exchangerates/rates/a/jpy/'))->rates[0]->mid;
break;
case 4:
$przelicznik = json_decode(file_get_contents('http://api.nbp.pl/api/exchangerates/rates/a/gbp/'))->rates[0]->mid;
break;
case 5:
$przelicznik = json_decode(file_get_contents('http://api.nbp.pl/api/exchangerates/rates/a/aud/'))->rates[0]->mid;
break;
default:
$przelicznik = 1;
}
$wynik = $_POST['kwota']/$przelicznik;
echo $wynik;
}
?>

Answer 1

The API is public, so you tecnically don't need PHP to do so, you can fetch the exchange rate and show the results using javascript/jQuery directly.
Here's an example on how to do so using jQuery:
<form id="exchange">
<input type="text" name="price" title="price">
<select name="currency" title="currency">
<option value="1">USD</option>
<option value="2">EUR</option>
<option value="3">JPY</option>
<option value="4">GBP</option>
<option value="5">AUD</option>
</select>
<input type="submit" value="calculate">
</form>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$('#exchange').on('submit',function(e){
e.preventDefault();
var value = $(this).find('[name="price"]').val();
if(!value) {
alert("Insert a valid value");
return false;
}
switch ($(this).find('[name="currency"]').val()) {
case "1":
$link = 'http://api.nbp.pl/api/exchangerates/rates/a/usd/';
break;
case "2":
$link = 'http://api.nbp.pl/api/exchangerates/rates/a/eur/';
break;
case "3":
$link = 'http://api.nbp.pl/api/exchangerates/rates/a/jpy/';
break;
case "4":
$link = 'http://api.nbp.pl/api/exchangerates/rates/a/gbp/';
break;
case "5":
$link = 'http://api.nbp.pl/api/exchangerates/rates/a/aud/';
break;
default:
alert('Error');
return false;
}
console.log($link);
$.getJSON($link,function(result){
alert(value/result.rates[0].mid);
});
});
</script>