javascript - 如何获取对象的属性名称并在javascript中使用该属性名称

Question

我有一个名为:mapped_errors 的对象，它返回一个动态对象。

有时它的值是:

{ _id:
   { location: 'body',
     param: '_id',
     value: 123,
     msg: '_id is required and must be a string' } }

有时它的值是:

{ _name:
   { location: 'body',
     param: '_name',
     value: 123,
     msg: '_name is required and must be a string' } }

我想输出这样的msg值:

let obj_key = Object.keys(mapped_errors);
console.log(mapped_errors.{obj_key}.msg); // i know this is wrong

;-)

Answer 1

代码中唯一的错误是 mapped_errors.{obj_key}.msg。当您使用变量获取键名时，您应该使用 [] 访问对象的属性值，如 mapped_errors[obj_key]。

var mapped_errors = { _id:
   { location: 'body',
     param: '_id',
     value: 123,
     msg: '_id is required and must be a string' } };

let obj_key = Object.keys(mapped_errors);
console.log(mapped_errors[obj_key].msg);

mapped_errors = { _name:
   { location: 'body',
     param: '_name',
     value: 123,
     msg: '_name is required and must be a string' } }
     
obj_key = Object.keys(mapped_errors);
console.log(mapped_errors[obj_key].msg);