JavaScript - Types, Equality, Conversion and All That Jazz: Serious types(equality(==), strict equality(===), converting(number, string, boolean))

Head First JavaScript Programming
( O'Reilly Media)
Eric T. Freeman (著), Elisabeth Robson (著)

開発環境

• OS X Mavericks - Apple(OS)
• Safari, Firefox + Firebug, Google Chrome(Webプラウザ、プラグイン)
• BBEdit - Bare Bones Software, Inc. (GUI) , Emacs (CUI) (Text Editor)
• JavaScript (プログラミング言語)

Head First JavaScript Programming (Eric T. Freeman (著)、 Elisabeth Robson (著)、 O'Reilly Media )のChapter 7(Types, Equality, Conversion and All That Jazz: Serious types)、SHARPEN YOUR PENCIL(p.280)を解いてみる。

SHARPEN YOUR PENCIL(p.280)

すべてundefined。

確認。

コード(BBEdit, Emacs)

print("42" == 42) // 42 == 42 true
print("42" === 42) // false
print("0" == 0) // 0 == 0 true
print("0" === 0) // false
print("0" == false) // "0" == 0 0 == 0 true
print("0" === false) // false
print("true" == true) // "true" == 1 NaN == 1 false
print("true" === true) // false
print(true == (1 == "1")) // true == (1 == 1) true == true true
print(true === (1 === "1")) // false