jQuery ajax问题

I don't have any expirience in ajax functions of jQuery. I'm trying to make simple call like:

$.get ("ajaxsupport/login");

I have a servlet with url-pattern ("ajaxsupport/login").

When I type in browser's address field "http://localhost:9090/ajaxsupport/login" I see some result. But $.get (..) doesn't even make a call.

What is the problem?

I use jquery 1.3.1

$.get is an asynchronous method call by default, meaning the caller remains in control. That's why something must happen, when the request has been executed. You specify that by defining a callback.

jQuery.get( url, [data], [callback], [type] )

In your case (note the prepended '/', it may not be necessary, depending on the scripts location, though):

<script type="text/javascript" charset="utf-8">
$(document).ready(function(){

    $.get("/ajaxsupport/login", 
        function(data, textStatus){ 
            // just prompt the response and the status message
            alert(data + "
" + textStatus); 
        } 
    );

});
</script>

Get a tool like fiddler. Watch at how the request goes over the wire. Is it going to where you think it's going? Are you getting a response? Can you put a breakpoint on your web service call?

Try to find out if you get a result:

$(document).ready(function(){
 $.ajax
 ({
    type: "GET",
    url:"/ajaxsupport/login",
    success: function(result)
    {
        alert("I'm a success");
    }
});

});

You can also use firebug to what is requested and returned.

**Two Variable asynchronous sending to server [Raw JavaScript || Jquery ]] **

var demo = document.querySelector('#demo');
var x = 0;
var y = 0;


//pure
demo.innerHTML = x;
demo.addEventListener('click',()=> {
    x=5;
    demo.innerHTML = x;
    var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function () {
        if (this.readyState == 4 && this.status == 200) {
            console.log(xhttp.responseText);
        }
    };
    xhttp.open("POST", 'http://localhost/target/index.php', true);
    xhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xhttp.send('data='+[x,y]);
});

//framework
$('#demo2').html(y);
$('#demo2').click(()=>{
    y=5;
    $.ajax({
        type: 'post',
        url: 'http://localhost/target/index.php',
        data: {
            'y': y,
            'x' : x
        },
        success: function (response) {
            console.log(response);
        },
        error: function () {
            console.log("error");
        }
    });
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #demo,#demo2{
            height: 100px;
            width: 100px;
            background-color: #f12100;
        }
        #demo2{
            background-color: #20c997;
        }
    </style>
</head>
<body>
<div id="demo"></div>
<br>
<div id="demo2"></div>
<script
        src="https://code.jquery.com/jquery-3.4.1.min.js"
        integrity="sha256-CSXorXvZcTkaix6Yvo6HppcZGetbYMGWSFlBw8HfCJo="
        crossorigin="anonymous"></script>
<script type="text/javascript" src="script.js"></script>
</body>
</html>

</div>