JavaScript

// 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?
*/