typeof是报告字符串而不是数字

Question

不知何故，其中包含数据4的变量报告为带有typeof运算符而不是数字的字符串？这是Code Academy编辑器的任何问题吗？

http://i.imgur.com/Os8n0dJ.png?1

var languages = {
    english: "Hello!",
    french: "Bonjour!",
    notALanguage: 4,
    spanish: "Hola!"
};

// print hello in the 3 different languages
for(var item in languages) {
    if(typeof item !== "number") {
        console.log(languages[item] + " " + typeof item);
    }
}

Answer 1

item是对象languages中的键，而不是这些属性的值。要检查您需要测试的值的类型languages[item]

// print hello in the 3 different languages
for(var item in languages) {
    if(typeof languages[item] !== "number") {
        console.log(languages[item] + " " + typeof item, item);
    }
}

演示：Fiddle

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