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AJAX PHP

The following example illustrates how a web page can communicate with a web server while a user types characters in an input field.

Example

<!DOCTYPE html>

<html>

<body>

<h2>The XMLHttpRequest Object</h2>

<h3>Start typing a name in the input field below:</h3>

<p>Suggestions: <span id=”txtHint”></span></p>

<p>First name: <input type=”text” id=”txt1″ onkeyup=”showHint(this.value)”></p>

<script>

function showHint(str) {

  if (str.length == 0) {

document.getElementById(“txtHint”).innerHTML = “”;

    return;

  }

const xhttp = new XMLHttpRequest();

xhttp.onload = function() {

document.getElementById(“txtHint”).innerHTML =

    this.responseText;

  }

  xhttp.open(“GET”, “gethint.php?q=”+str);

  xhttp.send();  

}

</script>

</body>

</html>

Output

The XMLHttpRequest Object

Start typing a name in the input field below:

Suggestions:

First name:

Code explanation

First, check whether the input field is empty (str.length == 0). If it is, then clear the content of the txtHint placeholder and exit the function.

In case the input field is not empty, then process the following:

  • Built an XMLHttpRequest object.
  • Built the function to be executed when the server response is ready.
  • Send the request off to a PHP file (gethint.php) on the server.
  • Notice that q parameter is added gethint.php?q=”+str.
  • The str variable stores the content of the input field.

The PHP File – “gethint.php”

The PHP file checks an array of names, and returns the corresponding name(s) to the browser.

<?php

// Array with names

$a[] = “Anna”;

$a[] = “Brittany”;

$a[] = “Cinderella”;

$a[] = “Diana”;

$a[] = “Eva”;

$a[] = “Fiona”;

$a[] = “Gunda”;

$a[] = “Hege”;

$a[] = “Inga”;

$a[] = “Johanna”;

$a[] = “Kitty”;

$a[] = “Linda”;

$a[] = “Nina”;

$a[] = “Ophelia”;

$a[] = “Petunia”;

$a[] = “Amanda”;

$a[] = “Raquel”;

$a[] = “Cindy”;

$a[] = “Doris”;

$a[] = “Eve”;

$a[] = “Evita”;

$a[] = “Sunniva”;

$a[] = “Tove”;

$a[] = “Unni”;

$a[] = “Violet”;

$a[] = “Liza”;

$a[] = “Elizabeth”;

$a[] = “Ellen”;

$a[] = “Wenche”;

$a[] = “Vicky”;

// get the q parameter from URL

$q = $_REQUEST[“q”];

$hint = “”;

// lookup all hints from array if $q is different from “”

if ($q !== “”) {

  $q = strtolower($q);

  $len=strlen($q);

  foreach($a as $name) {

    if (stristr($q, substr($name, 0, $len))) {

      if ($hint === “”) {

        $hint = $name;

      } else {

        $hint .= “, $name”;

      }

    }

  }

}

// Output “no suggestion” if no hint was found or output correct values

echo $hint === “” ? “no suggestion” : $hint;

?>


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