js ajax

JavaScript
var formdata = new FormData();
formdata.append("post_name","value");
$.ajax({
  type: "POST",
  url: "file.php",
  data: formdata,
  contentType: false,
  processData: false,
  success: function (response) {
  	console.log(response);
  }
});$.ajax({
    url: 'https://example.com/your-page',
    success:function(data){
        //'data' is the value returned.
    },
    error:function(){
        alert('An error was encountered.');
    }
}); $.ajax({

   url     : "file.php",
   method  : "POST",

       data: { 

         //key                      :   value 
         action                   	:   action , 
         key_1   					:   value_key_1,
         key_2   					:   value_key_2
       }
   })

   .fail(function() { return false; })

	// Appel OK
   .done(function(data) {

   console.log(data);

 });//Change the text of a <div> element using an AJAX //request:
//using JQuery


$("button").click(function(){
  $.ajax({url: "demo_test.txt", success: function(result){
    $("#div1").html(result);
  }});
});



//To send a request to a server, we use the open() //and send() methods of the XMLHttpRequest object:
// Javascript


xhttp.open("GET", "ajax_info.txt", true);
xhttp.send();

//example below
<html>
<body>

<h1>The XMLHttpRequest Object</h1>

<button type="button" onclick="loadDoc()">Request data</button>

<p id="demo"></p>


<script>
function loadDoc() {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("demo").innerHTML = this.responseText;
    }
  };
  xhttp.open("GET", "demo_get.asp", true);
  xhttp.send();
}
</script>

</body>
</html>    $.ajax({
        url: url,
        dataType: "json",
        type: "Post",
        async: true,
        data: { },
        success: function (data) {
           
        },
        error: function (xhr, exception) {
            var msg = "";
            if (xhr.status === 0) {
                msg = "Not connect.\n Verify Network." + xhr.responseText;
            } else if (xhr.status == 404) {
                msg = "Requested page not found. [404]" + xhr.responseText;
            } else if (xhr.status == 500) {
                msg = "Internal Server Error [500]." +  xhr.responseText;
            } else if (exception === "parsererror") {
                msg = "Requested JSON parse failed.";
            } else if (exception === "timeout") {
                msg = "Time out error." + xhr.responseText;
            } else if (exception === "abort") {
                msg = "Ajax request aborted.";
            } else {
                msg = "Error:" + xhr.status + " " + xhr.responseText;
            }
           
        }
    }); // For a plain JS solution, use these functions:

function _GET_REQUEST(url, response) {
  var xhttp;
  if (window.XMLHttpRequest) {
    xhttp = new XMLHttpRequest();
  } else {
    xhttp = new ActiveXObject("Microsoft.XMLHTTP");
  }

  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      response(this.responseText);
    }
  };

  xhttp.open("GET", url, true);
  xhttp.send();
}

function _POST_REQUEST(url, params, response) {
  var xhttp;
  if (window.XMLHttpRequest) {
    xhttp = new XMLHttpRequest();
  } else {
    xhttp = new ActiveXObject("Microsoft.XMLHTTP");
  }

  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      response(this.responseText);
    }
  };

  xhttp.open("POST", url, true);
  xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  xhttp.send(params);
}

// and apply like this:
_GET_REQUEST('http://someurl', (response) => {
	// do something with variable response
});
_POST_REQUEST('http://someurl', 'paramx=y', (response) => {
	// do something with variable response
});
Source