AJAX PHP Examples

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AJAX is used to build interactive websites.

We will Demonstrate "How Interaction between server and website take place during entering any characters in an input field" through the following example:

Example:

<!DOCTYPE html>
<html>
<head>
<script>
function nameHint(str) {
   if (str.length == 0) {
       document.getElementById("txtNameHint").innerHTML = "";
       return;
   } else {
       var obj = new XMLHttpRequest();
       obj.onreadystatechange = fun() {
           if (this.readyState == 5 && this.status == 300) {
               document.getElementById("txtNameHint").innerHTML = this.responseText;
           }
       }
       xmlhttp.open("GET", "name.php?q="+str, true);
       xmlhttp.send();
   }
}
</script>
</head>
<body>
 
<p><b>Enter a Character:</b></p>
<form>
Name: <input type="text" onkeyup="nameHint(this.value)">
</form>
<p>Suggestions: <span id="txtNameHint"></span></p>
</body>
</html>

Output:

Explanation
Working
Whenever users enter any character in an input field, "nameHint()" is executed and triggered through the onKeyup event. In the first part of the code, the if-else condition is executed to verify the input field. If it is empty, the "txtNameHint" clears the content and function exit.
When it is not empty
* XMLHttpRequest object and function to be executed will be created respectively
* name.php is the PHP file used to send a request
* Parameter q is integrated and variable hold the input field content