在 JavaScript 中获取对象的键和值？
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Get key and value of object in JavaScript?
提问by flossfan
Given a JavaScript array of objects, how can I get the key and value of each object?
给定一个 JavaScript 对象数组，如何获取每个对象的键和值？
The code below shows what I'd like to do, but obviously doesn't work:
下面的代码显示了我想做的事情，但显然不起作用：
var top_brands = [ { 'Adidas' : 100 }, { 'Nike' : 50 }];
var brand_options = $("#top-brands");
$.each(top_brands, function() {
brand_options.append($("<option />").val(this.key).text(this.key + " " + this.value));
});
So, how can I get this.keyand this.valuefor each entry in the array?
所以，我怎样才能得到this.key与this.value该阵列中的每个条目？
回答by Tomalak
Change your object.
改变你的对象。
var top_brands = [
{ key: 'Adidas', value: 100 },
{ key: 'Nike', value: 50 }
];
var $brand_options = $("#top-brands");
$.each(top_brands, function(brand) {
$brand_options.append(
$("<option />").val(brand.key).text(brand.key + " " + brand.value)
);
});
As a rule of thumb:
根据经验：
- An object has dataand structure.
'Adidas','Nike',100and50are data.- Object keys are structure. Using data as the object key is semantically wrong. Avoid it.
- 对象具有数据和结构。
'Adidas'、'Nike'、100和50是数据。- 对象键是结构。使用数据作为对象键在语义上是错误的。躲开它。
There are no semantics in {Nike: 50}. What's "Nike"? What's 50?
中没有语义{Nike: 50}。什么是“耐克”？什么是50？
{key: 'Nike', value: 50}is a little better, since now you can iterate an array of these objects and values are at predictable places. This makes it easy to write code that handles them.
{key: 'Nike', value: 50}好一点，因为现在您可以迭代这些对象的数组，并且值位于可预测的位置。这使得编写处理它们的代码变得容易。
Better still would be {vendor: 'Nike', itemsSold: 50}, because now values are not only at predictable places, they also have meaningful names. Technically that's the same thing as above, but now a person would also understand what the values are supposed to mean.
更好的是{vendor: 'Nike', itemsSold: 50}，因为现在值不仅位于可预测的位置，它们还有有意义的名称。从技术上讲，这与上述相同，但现在人们也会理解这些值的含义。
回答by thecodeparadox
$.each(top_brands, function() {
var key = Object.keys(this)[0];
var value = this[key];
brand_options.append($("<option />").val(key).text(key + " " + value));
});
回答by Graham
If this is all the object is going to store, then best literal would be
如果这就是对象要存储的全部内容，那么最好的文字是
var top_brands = {
'Adidas' : 100,
'Nike' : 50
};
Then all you need is a for...inloop.
那么你所需要的只是一个for...in循环。
for (var key in top_brands){
console.log(key, top_brands[key]);
}
回答by xdazz
$.each(top_brands, function(index, el) {
for (var key in el) {
if (el.hasOwnProperty(key)) {
brand_options.append($("<option />").val(key).text(key+ " " + el[key]));
}
}
});
But if your data structure is var top_brands = {'Adidas': 100, 'Nike': 50};, then thing will be much more simple.
但是如果你的数据结构是var top_brands = {'Adidas': 100, 'Nike': 50};，那么事情会简单得多。
for (var key in top_brands) {
if (top_brands.hasOwnProperty(key)) {
brand_options.append($("<option />").val(key).text(key+ " " + el[key]));
}
}
Or use the jquery each:
或者使用 jquery 每个：
$.each(top_brands, function(key, value) {
brand_options.append($("<option />").val(key).text(key + " " + value));
});
回答by Harish
for (var i in a) {
console.log(a[i],i)
}
回答by Jakob
Object.keys(top_brands).forEach(function(key) {
var value = top_brands[key];
// use "key" and "value" here...
});
Btw, note that Object.keysand forEachare not available in ancient browsers, but you should use some polyfill anyway.
顺便说一句，请注意Object.keys和forEach在古代浏览器中不可用，但无论如何您应该使用一些polyfill。
