javascript为什么word返回一个数组和word[0]未定义的javascript

Question

我正在努力使我的网站成为双语网站。所以我想迭代我的JS对象翻译。我可以用以下代码迭代：

for (var word of translation) {
console.log(word);
}   

但后来我得到了这个：

从我使用这个代码的那一刻起，我就没有定义

for (var word of translation) {
console.log(word[0]);
}   

这是我的目标型号

translation = [ 
{ English : [ ["English" , "engels"], ["lblEng",""] ]}, 
{dutch : [["dutch" , "nederlands"], ["lblNl",""]]},
{ second : [["second","seconde"], ["sec",""]]},
{minut : [["minut", "minut"],["min",""]]},
{ hour : [["hour","uur"],["h",""]]},
{ day :[ ["day", "dag"],["d",""]]}, 
{ to : [["to", "naar"],["to",""]]},
{ from : [["from", "van"],["from",""]]}
]

Answer 1

for...of对数组中的值(即对象(进行交互。例如第一次迭代，word={ English : [ ["English" , "engels"], ["lblEng",""] ]}

因此，当您执行word[0]时，它是undefined，因为在word对象中没有0属性

Answer 2

for (var word of translation) {
console.log(word[0]);
}  

变量word将分配一个对象，如下所示：

{ English : [ ["English" , "engels"], ["lblEng",""] ]}

因此，word[0]返回undefined，因为对象没有属性0。

也许，你真正想做的是：

const translation = [ 
{ English : [ ["English" , "engels"], ["lblEng",""] ]}, 
{dutch : [["dutch" , "nederlands"], ["lblNl",""]]},
{ second : [["second","seconde"], ["sec",""]]},
{minut : [["minut", "minut"],["min",""]]},
{ hour : [["hour","uur"],["h",""]]},
{ day :[ ["day", "dag"],["d",""]]}, 
{ to : [["to", "naar"],["to",""]]},
{ from : [["from", "van"],["from",""]]}
];

for (let word of translation) {
// get the keys and values and loop over them.
Object.entries(word).forEach(([lang, values]) => {
//values[0] returns the first index, so you can access it as follow:
let [first] = values;
console.log(lang, first);

});
}

Answer 3

感谢您的所有反应/回答。。。

当然，这确实帮助了我前进，如果需要一段时间才能做出回应，因为我正在对我的网络应用程序进行进一步的划分。