JavaScript

 var dateDeserialize = function (dateStr) {
            var dt = new Date(parseInt(dateStr.substr(6)));
            return prependZero((dt.getMonth() + 1))
                + "/" + prependZero(dt.getDate())
                + "/" + dt.getFullYear()
                + " " + prependZero(dt.getHours())
                + ":" + prependZero(dt.getMinutes())
                + ":" + prependZero(dt.getSeconds());
        };

        var FixDateinJson = function (JsonStudents) {
            $.each(JsonStudents, function (i, JsonStudent) {
                $.each(JsonStudent.ClassesTaken, function (i, JsonClass) {
                    $.each(JsonClass.ExamesTaken, function (i, JsonExam) {
                        JsonExam.ExamTime = dateDeserialize(JsonExam.ExamTime);
                    });
                });
            });

            return JsonStudents;
        }

        var buildStudentTree = function (students) {

            var createTextNode = function (text,id) {
                var span = document.createElement("span");
                span.setAttribute("style", "margin-left: 2px");
                ($('<input>').attr('type', 'button').attr('id',id)
                .attr('value', text)).appendTo(span);
                return span;
            };

            var root = document.createElement("ul");
            root.id = "StudentTreeRoot";
            root.setAttribute("style", "margin: 15px");
            root.className = "filetree";
            $.each(students, function (i, student) {
                var studentNode = document.createElement("li");
                studentNode.className = "closed";
                var span = document.createElement("span");
                span.className = "folder";
                span.appendChild(createTextNode(student.Name, 's'+(i+1)));
                studentNode.appendChild(span);

                var classesNode = document.createElement("ul");
                $.each(student.ClassesTaken, function (j, aClass) {
                    var classNode = document.createElement("li");
                    classNode.className = "closed";
                    span = document.createElement("span");
                    span.className = "folder";
                    span.appendChild(createTextNode(aClass.Name, 'c' + (i+1)));
                    classNode.appendChild(span);

                    var examesNode = document.createElement("ul");
                    examesNode.className = "folder";

                    $.each(aClass.ExamesTaken, function (k, aExam) {
                        var examNode = document.createElement("li");
                        examNode.className = "closed";
                        span = document.createElement("span");
                        span.className = "folder";
                        span.appendChild(createTextNode(aExam.Description, 'e' + (i + 1)));
                        examNode.appendChild(span);

                        var detailNode = document.createElement("ul");
                        var examTime = document.createElement("li");
                        span = document.createElement("span");
                        span.className = "file";
                        span.appendChild(createTextNode(aExam.ExamTime,'et'+(i+1)));
                        examTime.appendChild(span);
                        detailNode.appendChild(examTime);

                        var score = document.createElement("li");
                        span = document.createElement("span");
                        span.className = "file";
                        span.appendChild(createTextNode(aExam.Score, 'es'+(i+1)));
                        score.appendChild(span);
                        detailNode.appendChild(score);

                        examNode.appendChild(detailNode);

                        examesNode.appendChild(examNode);
                    });

                    classNode.appendChild(examesNode)

                    classesNode.appendChild(classNode);
                });

                studentNode.appendChild(classesNode);
                root.appendChild(studentNode);
            });

            $("#StudentTree").html("").append(root);
            $("#StudentTreeRoot").treeview();
        };

        $(document).ready(function () {
            $("#StudentTree").html("");
            $.ajax({
                cache: false,
                type: "POST",
                async: false,
                url: GetStudentsURL
                    + "/?NoOfStudents=" + NoOfStudents
                    + "&NoOfClasses=" + NoOfClasses
                    + "&NoOfExams=" + NoOfExams,
                dataType: "json",
                success: function (students) {
                    StudentJson = FixDateinJson(students);
                    buildStudentTree(StudentJson);
                }
            });

            $("#btnAddAnExamJson").click(function () {
                $("#StudentTree").html("Loading ...");

                $.ajax({
                    cache: false,
                    type: "POST",
                    url: AddAnExamByJsonURL,
                    contentType: 'application/json',
                    dataType: "json",
                    data: JSON.stringify(StudentJson),
                    success: function (students) {
                        StudentJson = FixDateinJson(students);
                        buildStudentTree(StudentJson);
                    }
                });
            });

            $("#btnAddAnExamSession").click(function () {
                $("#StudentTree").html("Loading ...");

                $.ajax({
                    cache: false,
                    type: "POST",
                    url: AddAnExamBySessionURL,
                    dataType: "json",
                    success: function (students) {
                        StudentJson = FixDateinJson(students);
                        buildStudentTree(StudentJson);
                    }
                });
            });

            $("#s1, #s2, #s3, #c1, #c2, #c3, #e1, #e2, #e3").click(function () {
                alert($(this).attr('id') + ' Clicked');
                $.ajax({
                    cache: false,
                    type: "POST",
                    //url: AddAnExamBySessionURL,
                    dataType: "json",
                    success: function (students) {
                        StudentJson = FixDateinJson(students);
                        buildStudentTree(StudentJson);
                        
                    }
                });
            });
        });
    </script>
</head>

<body>
    <div id="TitleContainer"><%= ViewData["ApplicationTitle"]%></div>
    <div id="MainContainer">
        <div id="StudentTree"></div>
        <div id="ButtonContainer">
            <button id="btnAddAnExamSession" class="ButtonStyle">
                Add an exam to students using session</button>
            <button id="btnAddAnExamJson" class="ButtonStyle">
                Add an exam to students by posting Json</button>
        </div>
    </div>
</body>
</html>

// Your use of the YouTube API must comply with the Terms of Service:
// https://developers.google.com/youtube/terms

// Helper function to display JavaScript value on HTML page.
function showResponse(response) {
    var responseString = JSON.stringify(response, '', 2);
    document.getElementById('response').innerHTML += responseString;
}

// Called automatically when JavaScript client library is loaded.
function onClientLoad() {
    gapi.client.load('youtube', 'v3', onYouTubeApiLoad);
}

// Called automatically when YouTube API interface is loaded (see line 9).
function onYouTubeApiLoad() {
    // This API key is intended for use only in this lesson.
    // See https://goo.gl/PdPA1 to get a key for your own applications.
    gapi.client.setApiKey('API_KEY');

    search();
}

function search() {
    // Use the JavaScript client library to create a search.list() API call.
    var request = gapi.client.youtube.search.list({
        part: 'snippet',
        q: "paper towel review",
        maxResults: 2,
        order: "viewCount"
    });

    // Send the request to the API server,
    // and invoke onSearchRepsonse() with the response.
    request.execute(onSearchResponse);
}

// Called automatically with the response of the YouTube API request.
function onSearchResponse(response) {
    showResponse(response);
}

var target = prompt("Please enter a number small than 50:");

        var guess = "";
        var time = 0;

        /*
        var guess2 = prompt("111");
        var guess3 = window.prompt("222",guess3);
        document.write(typeof(guess));
        document.write(typeof(guess2));
        document.write(typeof(guess3));
        */

        do{
            guess = prompt("Please Guess:");
            if(guess == target || guess == null){
                break;
            }

            if(guess < target){
                alert("bigger!");
                time++;
                continue;
            }else{
                alert("smaller!");
                time++;
                continue;
            }
        }while(true)

        if(guess==null){
            document.write("the answer is:"+target);
        }else{
            document.write("Good!共猜了:"+(time+1));
        }

/*
Dear all,

<!-- code -->
<script>
        function Array2D(x,y){
            this.length = x*y; 
            this.x = x;
            this.y = y;

            for(var i=0 ; i<this.length ; i++){
                this[i] = null;  
            }
            this.get = function(x,y){ 
                return this[x*this.x+y];
            }
            this.set = function(x,y,value){ 
                this[x*this.x+y] = value;

            }
        }
</script>

<script>
        var a2d = Array2D(10,10);
        a2d.set(2,3,"2");
        alert(this.get(1,2));
</script>
<!-- end code -->

<!-- error message -->
Uncaught TypeError: Cannot read property 'set' of undefined


How does it happen?and what should i do to avoid this?
*/