javascript - 接口(interface)上类型 'string' 的索引签名无法识别( typescript )

Question

我有这个代码:

const sectionInstance: FieldValues = sectionInstances[i]
for (const field in sectionInstance) {
    console.log(sectionInstance[field])
}

field这里当然是一个字符串。这是 FieldValues 的类型定义:

export interface FieldValues = {
  [key: string]: FieldValue;
}

我仍然收到此错误:

Element implicitly has an 'any' type because expression of type'string' can't be used to index type 'FieldValues'. No indexsignature with a parameter of type 'string' was found on type'FieldValues'.Vetur(7053)

我不是为 interface FieldValues 声明了“字符串”类型的索引签名吗？ ?为什么我会收到此错误？

Answer 1

只需删除 =从接口(interface)定义。
Please take a look at playground

interface FieldValues {
  [key: string]: FieldValue;
}
...
const sectionInstance: FieldValues = sectionInstances[i];
for (const field in sectionInstance) {
  console.log(sectionInstance[field]);
}