用jquery调用ajax时 type为post、put、get、delete之间的区别？

前台：

        $.ajax({
            type: "put",
            url: "Handler/Login.ashx",
            data: { "act": "islogin" },
            dataType: "html",
            success: function (mes) {
                if (mes == null) {
                    $('#title').html("用户信息");
                    $('#userInformation').addClass("yis");
                    $('#userlogin').removeClass("yis");
                }
            }
        });
        return false;
    });

 

后台：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Web.Model;
using System.Web.SessionState;



namespace Web.Handle
{
    /// <summary>
    /// Login 的摘要说明
    /// </summary>
    public class Login : IHttpHandler,IReadOnlySessionState
    {
        BookstoreDBEntities bookstore = new BookstoreDBEntities();
        public void ProcessRequest(HttpContext context)
        {
            string act = context.Request.Params["act"];
            if (act == "login")
            {
                string userName = context.Request.Params["userName"];
                string password = context.Request.Params["password"];
                var model = bookstore.User_Tbl.First(u => u.userName == userName);
                if (model == null)
                {
                    string mes = "用户不存在!";
                    context.Response.Write(mes);
                }
                else
                {
                    if (model.password != password)
                    {
                        string mes = "密码错误!";
                        context.Response.Write(mes);
                    }
                    else
                    {
                        context.Response.Write(userName);
                        context.Session["userName"] = userName;
                    }
                }
            }
            else if (act == "islogin")
            {
                //if (context.Session["userName"] == null)
                //    context.Response.Write(null);
                //else
                    context.Response.Write(context.Session["userName"]);
            }
            context.Response.Clear();
            context.Response.Close();
        }

 

 

刚开始时ajax的type我用的是post 然后就一直报错、后面改成put就通过了，表示不是很理解。

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现在看起来当时好傻，按照HTTP的标准协议put是提交修改的，post是提交数据库新加内容的，get是获取查询，delete是删除信息。