PHP -AJAX and PHP
AJAX is used to create more interactive applications.
AJAX PHP Example
The following example will demonstrate how a web page can communicate with a web server while a user type characters in an input field:
Example
Start typing a name in the input field below:
Suggestions:
Example Explained
In the example above, when a user types a character in the input field, a function calledshowHint() is executed.
The function is triggered by the onkeyup event.
Here is the HTML code:
Example
<html><head><script>function showHint(str) { if (str.length == 0) { document.getElementById("txtHint").innerHTML = ""; return; } else { var xmlhttp = new XMLHttpRequest(); xmlhttp.onreadystatechange = function() { if (this.readyState == 4 && this.status == 200) { document.getElementById("txtHint").innerHTML = this.responseText; } }; xmlhttp.open("GET", "gethint.php?q=" + str, true); xmlhttp.send(); }}</script></head><body><p><b>Start typing a name in the input field below:</b></p><form action=""> <label for="fname">First name:</label> <input type="text" id="fname" name="fname" onkeyup="showHint(this.value)"></form><p>Suggestions: <span id="txtHint"></span></p></body></html>Code explanation:
First, check if the input field is empty (str.length == 0). If it is, clear the content of the txtHint placeholder and exit the function.
However, if the input field is not empty, do the following:
- Create an
XMLHttpRequestobject - Create 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
qparameter is added to the url(gethint.php?q=" + str) - And the
strvariable holds 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:
// 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 valuesecho $hint === "" ? "no suggestion" : $hint;
