プログラミング学習の記録 214 独習JavaScript (大型本)の第7章(オブジェクト指向プログラミング)の理解度チェック4

開発環境:
Mac OS X Snow Leopard (OS)
Firefox(ブラウザ)+Firebug(アドオン)

"独習JavaScript (大型本)"のp.249, 第7章(オブジェクト指向プログラミング)の理解度チェック4を解いてみる。

4.

var jp;
    if (!jp) {
        jp = {};
    }
    if (!jp.learnYourself) {
        jp.learnYourself = {};
    }
    jp.learnYourself.AbstractStringSplitter=function(str, spl) {
        this.str = str;
        this.spl = spl;
        this.array = this.getArray();
        this.pos = -1;
    }
    jp.learnYourself.AbstractStringSplitter.prototype.getArray = function () {
        return this.str.split(this.spl);
    };
    jp.learnYourself.AbstractStringSplitter.prototype.getNext = function () {
        this.pos += 1;
        if (this.pos >= this.array.length) {
            this.pos = -1;
            return null;
        }
        return this.array[this.pos];
    };
    function SlashStringSplitter(str) {
        jp.learnYourself.AbstractStringSplitter.apply(this, [str, "/"]);
    }
    function CommaStringSplitter(str) {
        jp.learnYourself.AbstractStringSplitter.apply(this, [str, ","]);
    }
    SlashStringSplitter.prototype = new jp.learnYourself.AbstractStringSplitter("tmp", "/");
    delete SlashStringSplitter.prototype.str;
    delete SlashStringSplitter.prototype.spl;
    delete SlashStringSplitter.prototype.array;
    delete SlashStringSplitter.prototype.pos;
    SlashStringSplitter.prototype.constructor = SlashStringSplitter;
    var str = prompt("文字列を入力してください", "");
    var array = new SlashStringSplitter(str);
    alert("/で区切った配列の先頭の要素: " + array.getNext());
    CommaStringSplitter.prototype = new jp.learnYourself.AbstractStringSplitter("tmp", ",");
    delete CommaStringSplitter.prototype.str;
    delete CommaStringSplitter.prototype.spl;
    delete CommaStringSplitter.prototype.array;
    CommaStringSplitter.prototype.constructor = CommaStringSplitter;
    var array1=new CommaStringSplitter(str);
    alert(",で区切った配列の先頭の要素: "+ array.getNext());