$.ajax({
       type: "POST",
       contentType: "application/x-www-form-urlencoded",
       url: "http://website/index.php",
       data: { username: "myuser", password: "123456" },
       success: function(data) {
            console.log("success ", data.response);
        },
        error: function(data) {
            console.log("error ", data.error);
        },
        dataType: "html"
    });