How to send GET and POST AJAX request with JavaScript

AJAX is the only way that allows communicating client-side with the server-side.


It is easier to send AJAX requests using JavaScript libraries or frameworks. But it is also good to know how to send AJAX request with plain Javascript.

Use the XMLHttpRequest object to communicate with the server.

In this tutorial, I show how you can send GET and POST AJAX requests with JavaScript and handle the request with PHP.



1. Table structure

Create employee table and added some records.

CREATE TABLE `employee` ( `id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT, `emp_name` varchar(80) NOT NULL, `salary` varchar(20) NOT NULL, `email` varchar(80) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. Configuration

Create a config.php for the database connection.

Completed Code

<?php $host = "localhost"; /* Host name */
$user = "root"; /* User */
$password = ""; /* Password */
$dbname = "tutorial"; /* Database name */ $con = mysqli_connect($host, $user, $password,$dbname);
// Check connection
if (!$con) { die("Connection failed: " . mysqli_connect_error());
}

3. HTML

Create 3 input text elements for entering the name, salary, and email. And a button element.

Added onclick event on the button which calls insertNewEmployee() function.

List records in the <table id='emptTable'> using JavaScript and AJAX.

Completed Code

<div> Name: <input type="text" id='txt_name'> <br> Salary: <input type="text" id='txt_salary'> <br> Email: <input type="text" id='txt_email'> <br> <input type="button" id="btn_submit" value="Submit" onclick="insertNewEmployee();">
</div>
<table id='empTable' border='1'> <thead> <tr> <th>Name</th> <th>Salary</th> <th>Email</th> </tr> </thead> <tbody></tbody>
</table>

4. PHP

Create 'ajaxfile.php' file to handle AJAX request.

For example purpose, I am handling both GET and POST requests in the single file.

Assigned 2 to $request.

GET request (fetch records)

Check if $_GET['request'] is set or not if set then assign $_GET['request'] to $request.

If $request == 1 then fetch all records from employee table and assign in $employeeData. Loop on the fetched records.

Initialize $response with id, emp_name, salary, and email keys.

Return $response Array in JSON format.

POST request (insert record)

If $request == 2 then read POST values using json_decode(file_get_contents("php://input")).

Assing values to variables and prepare INSERT query.

If the INSERT query executed successfully then return 1 otherwise 0.

Completed Code

<?php include "config.php"; $request = 2; // Read $_GET value
if(isset($_GET['request'])){ $request = $_GET['request'];
} // Fetch records if($request == 1){ // Select record $sql = "SELECT * FROM employee"; $employeeData = mysqli_query($con,$sql); $response = array(); while($row = mysqli_fetch_assoc($employeeData)){ $response[] = array( "id" => $row['id'], "emp_name" => $row['emp_name'], "salary" => $row['salary'], "email" => $row['email'], ); } echo json_encode($response); exit;
} // Insert record
if($request == 2){ // Read POST data $data = json_decode(file_get_contents("php://input")); $name = $data->name; $salary = $data->salary; $email = $data->email; // Insert record $sql = "insert into employee(emp_name,salary,email) values('".$name."',".$salary.",'".$email."')"; if(mysqli_query($con,$sql)){ echo 1; }else{ echo 0; } exit;
}

5. JavaScript

Use XMLHttpRequest object to send AJAX request.

.open() – Methods takes 3 parameters –

  1. Request method – GET or POST.
  2. AJAX file path. Pass parameter with URL on GET request – ajaxfile.php?name=yogesh&city=bhopal.
  3. It is an optional parameter that takes Boolean value true or false. Default value is true. Pass true for asynchronous and false for synchronous request.

.setRequestHeader() – This method is used to set Content-Type. By default 'application/x-www-form-urlencoded' content-type is set. You can change its value e.g. – application/jsonmultipart/form-data, etc.

.onreadystatechange – This property calls on request state change. Assign an anonymous function to process the response. If this.readyState == 4 && this.status == 200 means server response is ready for processing.

.send() – This method send AJAX request. It is also used to send data.

  • GET syntax –
var xhttp = new XMLHttpRequest();
xhttp.open("GET", "ajaxfile.php?request=1", true);
xhttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xhttp.onreadystatechange = function() { if (this.readyState == 4 && this.status == 200) { // Response var response = this.responseText; }
};
xhttp.send();

Above syntax with jQuery

$.ajax({ url: 'ajaxfile.php?request=1', type: 'get', success: function(response){ }
});
  • POST syntax –

application/x-www-form-urlencoded; charset=UTF-8 is a default Content-Type but you can use any other type e.g. – application/jsonmultipart/form-data, etc.

var xhttp = new XMLHttpRequest();
xhttp.open("POST", "ajaxfile.php", true); xhttp.setRequestHeader("Content-Type", "application/json");
xhttp.onreadystatechange = function() { if (this.readyState == 4 && this.status == 200) { // Response var response = this.responseText; }
};
var data = {name:'yogesh',salary: 35000,email: '[email protected]'};
xhttp.send(JSON.stringify(data));

Above syntax with jQuery

$.ajax({ url: 'ajaxfile.php', type: 'post', data: {name:'yogesh',salary: 35000,email: '[email protected]'}, success: function(response){ }
});

Create 2 functions –

  • loadEmployees() – This function calls on page successfully loaded.

Create object of XMLHttpRequest. Specify GET request and AJAX file path with parameter ('ajaxfile.php?request=1') in .open() method. Set Content-type and handle server response with onreadystatechange property.

Parse the this.responseText to JSON object and select <table id='empTable'> <tbody> and empty it.

Loop on the response to read values. Create a new table row element and assign a response value in cell.

Send the request by calling send() method.

  • insertNewEmployee() – This function calls on Submit button click.

Read values from the textboxes and assign them in variables. If variables are not empty then create a data JSON object. Initialize data object with the textbox values.

Create XMLHttpRequest object and specify POST request and AJAX file path ('ajaxfile.php') in .open() method. Set Content-type to 'application/json' and handle server response with onreadystatechange property.

Assign this.responseText in response. If response == 1 then alert a message and call loadEmployees() function to fetch records.

Completed Code

loadEmployees(); // Load records with GET request
function loadEmployees() { var xhttp = new XMLHttpRequest(); // Set GET method and ajax file path with parameter xhttp.open("GET", "ajaxfile.php?request=1", true); // Content-type xhttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); // call on request changes state xhttp.onreadystatechange = function() { if (this.readyState == 4 && this.status == 200) { // Parse this.responseText to JSON object var response = JSON.parse(this.responseText); // Select <table id='empTable'> <tbody> var empTable = document.getElementById("empTable").getElementsByTagName("tbody")[0]; // Empty the table <tbody> empTable.innerHTML = ""; // Loop on response object for (var key in response) { if (response.hasOwnProperty(key)) { var val = response[key]; // insert new row var NewRow = empTable.insertRow(0); var name_cell = NewRow.insertCell(0); var username_cell = NewRow.insertCell(1); var email_cell = NewRow.insertCell(2); name_cell.innerHTML = val['emp_name']; username_cell.innerHTML = val['salary']; email_cell.innerHTML = val['email']; } } } }; // Send request xhttp.send();
} // Insert new record with POST request
function insertNewEmployee() { var name = document.getElementById('txt_name').value; var salary = document.getElementById('txt_salary').value; var email = document.getElementById('txt_email').value; if(name != '' && salary !='' && email != ''){ var data = {name: name,salary: salary,email: email}; var xhttp = new XMLHttpRequest(); // Set POST method and ajax file path xhttp.open("POST", "ajaxfile.php", true); // call on request changes state xhttp.onreadystatechange = function() { if (this.readyState == 4 && this.status == 200) { var response = this.responseText; if(response == 1){ alert("Insert successfully."); loadEmployees(); } } }; // Content-type xhttp.setRequestHeader("Content-Type", "application/json"); // Send request with data xhttp.send(JSON.stringify(data)); } }


6. Conclusion

With the use of XMLHttpRequest object send AJAX request.

In GET request directly pass data with a filename like – ajaxfile.php?name=yogesh&city=bhopal and in POST request pass your data in send() method.

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