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document.write を使用して、すべてのオブジェクト プロパティをコピーしてオブジェクト化し、出力する関数を作成する必要があります。

このような関数を作成したのですが、結果として [object Object] が返され、理由がわかりません。

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
    <script type="text/javascript">
        /********* GLOBAL VARIABLES *********/
        var BR = "<br />";
        var ES = " ";



        /********* FUNCTIONS *********/


        function compare(album0, album1) {

            //This seems to do exactly what's needed... but sadly I dont have time to test every possible scenario.
            var sameTracks = true;
            for (var i = 0; i < album0.length; i++) {
                if (!(album0.tracks[i] === album1.tracks[i])) sameTracks = false;
            }
            for (var i = 0; i < album1.length; i++) {
                if (!(album0.tracks[i] === album1.tracks[i])) sameTracks = false;
            }

            if (
            album0.artistName === album1.artistName && album0.albumTitle === album1.albumTitle && album0.releaseYear === album1.releaseYear && album0.ifHQ === album1.ifHQ && album0.tracks.length === album1.tracks.length && sameTracks === true) {
                return true
            }
            else {
                return false
            };
        }


        function copy(album1) //the copy function
        {


            //properties will be copied over from original album1 into copy
            var albumCopy = 
            {
                artistName: "",
                albumTitle: "",
                releaseYear: 0,
                ifHQ: "",
                tracks: undefined
            };
            //copies original object values item for item into duplicate album
            for (var key in albumCopy) 

            {
            albumCopy[key] = album1[key];
            }
            return albumCopy;
        }


        /********* MAIN *********/
        function main() {

            var album = new Array(2)






            for (var i = 0; i < album.length; i++) //ok, so basically this loop is responsible for creating the album objects...
            {
                album[i] = {
                    artistName: "",
                    albumTitle: "",
                    releaseYear: 0,
                    ifHQ: "",
                    tracks: undefined //tracks here
                };

                album[i].artistName = prompt("What is the artist's name?");
                album[i].albumTitle = prompt("What is the album title?");
                album[i].releaseYear = parseFloat(prompt("What is the album's release year"));
                album[i].ifHQ = prompt("Is the album high quality? Y/N");

                while (!(album[i].ifHQ === "Y" || album[i].ifHQ === "N" || album[i].ifHQ === "YES" || album[i].ifHQ === "NO")) //to handle bad input
                {
                    album[i].ifHQ = prompt("You have entered an invalid response. Is " + album[i].title + " a ifHQ album, Y/N?");
                    album[i].ifHQ = album[i].ifHQ.toUpperCase();
                }

                if (album[i].ifHQ === "Y") {
                    album[i].ifHQ = true;
                }
                else {
                    album[i].ifHQ = false;
                }

                album[i].tracks = new Array(2); // the tracks property of each album object is an array of tracks... 

                for (var j = 0; j < album[i].tracks.length; j++) {
                    album[i].tracks[j] = prompt("Enter track " + (j + 1));
                }
            }

            for (var key in album[0]) //and these for... in loops navigate through properties for these objects to output what was stored in them
            {
                document.write(key + ": " + album[0][key] + " ");
                document.write(BR);
            }
            for (var key in album[1]) {
                document.write(key + ": " + album[1][key] + " ");
                document.write(BR);
            }

            var same = compare(album[0], album[1]);
            document.write("The status of both albums being identical is" + ES + same + BR);
            var copiedAlbum = copy(album[1]);
            document.write(copiedAlbum);
        }



        // This line calls main, don't change it:
        main();







    </script>
</body>

4

2 に答える 2

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私のコメントのフォローアップとして、これがあなたがやろうとしていることをするためのより良い方法です：

// This code defines an "Album" class
function Album(artistName, albumTitle, releaseYear, ifHQ) {
    this.artistName = artistName;
    this.albumTitle = albumTitle;
    this.releaseYear = releaseYear;
    this.ifHQ = ifHQ;
    this.tracks = [];
};

// Album.prototype contains all methods available to Album objects
Album.prototype.addTrack = function(trackName) {
    this.tracks.push(trackName);
};

// alternative to compare() function
Album.prototype.equals = function(album) {
    if (this.artistName != album.artistName) return false;
    if (this.albumTitle != album.albumTitle) return false;
    if (this.releaseYear != album.releaseYear) return false;
    if (this.tracks.length != album.tracks.length) return false;

    for (var i = 0, len = this.tracks.length; i < len; i++) {
        if (this.tracks[i] != album.tracks[i]) return false;
    }

    return true;
};

// create our own custom toString method
Album.prototype.toString = function() {
    var str = "";
    str += "Artist: " + this.artistName;
    str += "Album: " + this.albumName;
    // you get the idea
    return str;
};



// MAIN
// create albums
var albums = []

var queen = new Album("Queen", "Queen", 1973, true);
var queen2 = new Album("Queen", "Queen II", 1974, true);
albums.push(queen, queen2);

var albumsAreTheSame = queen.equals(queen2); // test if queen == queen2

document.write(queen); // queen.toString() is automatically called

このコードは明らかに不完全です

于 2013-01-06T15:34:02.457 に答える
0

オブジェクトをコピーするには、Object.createメソッドを使用できます。次に、オブジェクトをループして、for inを使用してプロパティを出力できますdocument.write。たとえば、次を使用できます。

// For older browser's suppoet
if (typeof Object.create !== 'function') {
    Object.create = function (o) {
        function F() {}
        F.prototype = o;
        return new F();
    };
}

// an object
var album1={
    artistName: "",
    albumTitle: "",
    releaseYear: 0,
    ifHQ: "",
    tracks: undefined
};
// create a new object from album1/copy
var newAlbum=Object.create(album1);
// output the properties
for(var i in newAlbum) document.write(i+'<br />');

例。

于 2013-01-06T15:26:18.567 に答える