//比较两个数字，如果第一个数字大于第二个数字，则返回“微信”否则返回“qq function compare(num1, num2) { if (num1 > num2) { return"微信"; } else { return"qq"; } }
再来一个判断时间是星期几的函数
//根据时间判断星期几 function getWeek(date) { var week; switch (date.getDay()) { case 0: week = "星期日"; break; case 1: week = "星期一"; break; case 2: week = "星期二"; break; case 3: week = "星期三"; break; case 4: week = "星期四"; break; case 5: week = "星期五"; break; case 6: week = "星期六"; break; } return week; }
再来试试 http 请求写的怎么样，访问一下百度把html返回。
//返回baidu.com的html functiongetBaiduHtml() { var url = "http://www.baidu.com"; var xhr = new XMLHttpRequest(); xhr.open("GET", url, false); xhr.send(); var html = xhr.responseText; return html; }
JavaScript 操作 html 也很常见，那么试试查找元素怎么样
//查找页面上所有的div functionfindAllDiv() { var divs = document.getElementsByTagName("div"); return divs; }
//查找所有页面上class=user的input元素 functionfindAllUserInput() { var inputs = document.getElementsByClassName("user"); return inputs; }
再来试试 http 提交对象怎么样
//请求一个url，post一个json对象 function postJson(url, json) { var xhr = new XMLHttpRequest(); xhr.open("POST", url, false); xhr.setRequestHeader("Content-Type", "application/json"); xhr.send(JSON.stringify(json)); var response = xhr.responseText; return response; }
// 使用hls.js播放视频 function playVideo(video) { var hls = new Hls(); hls.loadSource("http://www.w3school.com.cn/i/movie.mp4"); hls.attachMedia(video); hls.on(Hls.Events.MANIFEST_PARSED, function () { video.play(); }); }
//使用EF查询用户 public static ListGetUserList() { using (var db = new CopiloteContext()) { return db.User.ToList(); } }
再来试试使用 dapper 的写法
//使用dapper查询用户 public static ListGetUserListDapper() { using (IDbConnection db = new SqlConnection("server=.;database=copilote;uid=sa;pwd=123456")) { return db.Query("select * from user").ToList(); } }
让我们加大难度，来个连接跟分组统计人数
//查询2020年每个班级学生的人数 public static void GetClassStudentCount() { using (IDbConnection db = new SqlConnection("server=.;database=copilote;uid=sa;pwd=123456")) { db.Query("select class.name as classname,count(student.id) as studentcount from student left join class on student.classid=class.id where class.year=2020 group by class.name").ToList(); } }
让它自动生成改删查操作
class student { public int id { get; set; } public string name { get; set; } public int classid { get; set; } }
//student的新增操作 public static void AddStudent(student s) { using (IDbConnection db = new SqlConnection("server=.;database=copilote;uid=sa;pwd=123456")) { db.Execute("insert into student(name,classid) values(@name,@classid)", s); } } //student的更新操作 public static void UpdateStudent(student s) { using (IDbConnection db = new SqlConnection("server=.;database=copilote;uid=sa;pwd=123456")) { db.Execute("update student set name=@name,classid=@classid where id=@id", s); } } //student的删除操作 public static void DeleteStudent(int id) { using (IDbConnection db = new SqlConnection("server=.;database=copilote;uid=sa;pwd=123456")) { db.Execute("delete from student where id=@id", new { id = id }); } }
再来试试生成 ASP.NET MVC 的 action 方法。
class UserController : Controller { //从 request 获取 name 参数查询用户，如果查到就返回否则返回状态404 public ActionResult GetUser(string name) { User user = UserService.GetUser(name); if (user != null) { return Json(user); } else { return HttpNotFound(); } }
