javascript 获取JS中单键未知的对象的值
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Get the value of an object with an unknown single key in JS
提问by Osama
How can I get the value of an object with an unknown single key?
如何获取具有未知单键的对象的值？
Example:
例子：
var obj = {dbm: -45}
I want to get the -45 value without knowing its key.
我想在不知道其键的情况下获得 -45 值。
I know that I can loop over the object keys (which is always one).
我知道我可以遍历对象键（总是一个）。
for (var key in objects) {
var value = objects[key];
}
But I would like to know if there is a cleaner solution for this?
但我想知道是否有更清洁的解决方案？
回答by Blauharley
Object.keys might be a solution:
Object.keys 可能是一个解决方案：
Object.keys({ dbm: -45}); // ["dbm"]
The differences between for-in and Object.keys is that Object.keys returns all own key names and for-in can be used to iterate over all own and inherited key names of an object.
for-in 和 Object.keys 的区别在于 Object.keys 返回所有自己的键名，而 for-in 可用于迭代对象的所有自有和继承的键名。
As James Brierley commented below you can assign an unknown property of an object in this fashion:
正如 James Brierley 在下面评论的那样，您可以以这种方式分配对象的未知属性：
var obj = { dbm:-45 };
var unkownKey = Object.keys(obj)[0];
obj[unkownKey] = 52;
But you have to keep in mind that assigning a property that Object.keys returns key name in some order of might be error-prone.
但是您必须记住，分配 Object.keys 以某种顺序返回键名的属性可能容易出错。
回答by T.J. Crowder
There's a new option now: Object.values. So if you knowthe object will have just one property:
现在有一个新选项：Object.values. 因此，如果您知道该对象将只有一个属性：
const array = Object.values(obj)[0];
Live Example:
现场示例：
const json = '{"EXAMPLE": [ "example1","example2","example3","example4" ]}';
const obj = JSON.parse(json);
const array = Object.values(obj)[0];
console.log(array);If you need to know the name of the property as well, there's Object.entriesand destructuring:
如果您还需要知道属性的名称，则有Object.entries和解构：
const [name, array] = Object.entries(obj)[0];
Live Example:
现场示例：
const json = '{"EXAMPLE": [ "example1","example2","example3","example4" ]}';
const obj = JSON.parse(json);
const [name, array] = Object.entries(obj)[0];
console.log(name);
console.log(array);