Native JS Ajax handles the full example of an asynchronous request for JSON data format __JS

Post-send data for example
    function Chufa () {//html element event-triggered
        var myxmlhttprequest = null;
        if (window. ActiveXObject) {
            myxmlhttprequest = new ActiveXObject ("Microsoft.XMLHTTP");
        } else {
            myxmlhttprequest = New XMLHttpRequest ();
        }
        var url = "xxx.php";
        var data = "Key=val"; Val is typically a value
        myxmlhttprequest.open ("post", url, True) removed from an HTML element;
        Myxmlhttprequest.setrequestheader ("Content-type", "application/x-www-form-urlencoded");
        Myxmlhttprequest.onreadystatechange = function () {
            if (myxmlhttprequest.readystate = 4 && Myxmlhttprequest.status = = {
                var res = myxmlhttprequest.responsetext;
                var jsonobj = eval ("+res+");
                You can then use the Jsonobj JSON object to remove the attribute values, do some modification of the HTML element value, and so on.
            }        
        }
        Myxmlhttprequest.send (data);
    }
</script