プログラミング学習の記録 293 "独習JavaScript"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

開発環境

• Microsoft Windows 7 Home Premium (OS)
• Internet Explorer 8 (プラウザ)
• Microsoft Visual Web Developer 2010 Express Edition (IDE)
• Script言語:JavaScript

"独習JavaScript"の第7章(オブジェクト指向プログラミング)のこの章の理解度チェックを解いてみる。

1.

オブジェクト指向の特徴は、クラスという設計図のようなものを定義し、それを実体化しながらプログラミングを進めていく。

 

2.

var CommaStringSplitter = function (str) { if (!str || str.length == 0) { throw new Error("文字列を指定してください"); } this.str = str; this.array = this.getArray(); this.pos = -1; }; CommaStringSplitter.prototype.getArray = function () { return this.str.split(","); }; CommaStringSplitter.prototype.getNext = function () { this.pos += 1; if (this.pos >= this.array.length) { this.pos = -1; return null; } return this.array[this.pos]; }; var str = "a,bb,ccc,dddd,eeeee"; var obj = new CommaStringSplitter(str); document.write("<p>str=" + str + "</p><p>カンマで区切って配列に格納: array=" + obj.array + "</p>"); document.write("<p>順番に配列の要素を出力(10回。最後で出力したら先頭に戻る)</p>"); for (var i = 0; i < 10; i++) { document.write("<p>" + obj.getNext() + "</p>"); }

 

3.

var AbstractStringSplitter = function (str, splitter) { if (!str || str.length == 0) { throw new Error("文字列を指定してください"); } this.str = str; this.splitter = splitter; this.array = this.getArray(); this.pos = -1; }; AbstractStringSplitter.prototype.getArray = function () { return this.str.split(this.splitter); }; AbstractStringSplitter.prototype.getNext = function () { this.pos += 1; if (this.pos >= this.array.length) { this.pos = -1; return null; } return this.array[this.pos]; }; var SlashStringSplitter = function (str) { AbstractStringSplitter.apply(this, [str, "/"]); } var CommaStringSplitter = function (str) { AbstractStringSplitter.apply(this, [str, ","]); } SlashStringSplitter.prototype = new AbstractStringSplitter("tmp", "/"); CommaStringSplitter.prototype = new AbstractStringSplitter("tmp", ","); delete SlashStringSplitter.prototype.str; delete SlashStringSplitter.prototype.splitter; delete SlashStringSplitter.prototype.array; delete SlashStringSplitter.prototype.pos; SlashStringSplitter.prototype.constructor = SlashStringSplitter; delete CommaStringSplitter.prototype.str; delete CommaStringSplitter.prototype.splitter; delete CommaStringSplitter.prototype.array; delete CommaStringSplitter.prototype.pos; CommaStringSplitter.prototype.constructor = CommaStringSplitter; var str = "a/bb,ccc/dddd,eeeee"; var obj1 = new SlashStringSplitter(str); var obj2 = new CommaStringSplitter(str); document.write("<p>str=" + str + "</p><p>スラッシュで区切って配列に格納: array1=" + obj1.array + "</p>"); document.write("<p>順番に配列の要素を出力(10回。最後で出力したら先頭に戻る)</p>"); for (var i = 0; i < 10; i++) { document.write("<p>" + obj1.getNext() + "</p>"); } document.write("<p>str=" + str + "</p><p>カンマで区切って配列に格納: array2=" + obj2.array + "</p>"); document.write("<p>順番に配列の要素を出力(10回。最後で出力したら先頭に戻る)</p>"); for (var i = 0; i < 10; i++) { document.write("<p>" + obj2.getNext() + "</p>"); }

 

4.

var jp; if (!jp) { jp = {}; } if (!jp.learnyourslef) { jp.learnyourslef = {}; } with (jp.learnyourslef) { var AbstractStringSplitter = function (str, splitter) { if (!str || str.length == 0) { throw new Error("文字列を指定してください"); } this.str = str; this.splitter = splitter; this.array = this.getArray(); this.pos = -1; }; AbstractStringSplitter.prototype.getArray = function () { return this.str.split(this.splitter); }; AbstractStringSplitter.prototype.getNext = function () { this.pos += 1; if (this.pos >= this.array.length) { this.pos = -1; return null; } return this.array[this.pos]; }; var SlashStringSplitter = function (str) { AbstractStringSplitter.apply(this, [str, "/"]); } var CommaStringSplitter = function (str) { AbstractStringSplitter.apply(this, [str, ","]); } SlashStringSplitter.prototype = new AbstractStringSplitter("tmp", "/"); CommaStringSplitter.prototype = new AbstractStringSplitter("tmp", ","); delete SlashStringSplitter.prototype.str; delete SlashStringSplitter.prototype.splitter; delete SlashStringSplitter.prototype.array; delete SlashStringSplitter.prototype.pos; SlashStringSplitter.prototype.constructor = SlashStringSplitter; delete CommaStringSplitter.prototype.str; delete CommaStringSplitter.prototype.splitter; delete CommaStringSplitter.prototype.array; delete CommaStringSplitter.prototype.pos; CommaStringSplitter.prototype.constructor = CommaStringSplitter; var str = "a/bb,ccc/dddd,eeeee"; var obj1 = new SlashStringSplitter(str); var obj2 = new CommaStringSplitter(str); document.write("<p>str=" + str + "</p><p>スラッシュで区切って配列に格納: array1=" + obj1.array + "</p>"); document.write("<p>順番に配列の要素を出力(10回。最後で出力したら先頭に戻る)</p>"); for (var i = 0; i < 10; i++) { document.write("<p>" + obj1.getNext() + "</p>"); } document.write("<p>str=" + str + "</p><p>カンマで区切って配列に格納: array2=" + obj2.array + "</p>"); document.write("<p>順番に配列の要素を出力(10回。最後で出力したら先頭に戻る)</p>"); for (var i = 0; i < 10; i++) { document.write("<p>" + obj2.getNext() + "</p>"); } }