TypeScript中如何遍历以枚举为索引的对象？

首先纠正你代码里的两个笔误：

• 枚举名拼写错误：FunnalStage → FunnelStage
• 枚举成员大小写错误：FunnelStage.Login → FunnelStage.LOGIN（枚举定义的是大写LOGIN）

错误根源是：TypeScript中for...in遍历对象时，键的默认类型是string，但你的overall对象的索引类型是FunnelStage枚举，类型不匹配导致报错。以下是几种正确的实现方式：

方法一：断言遍历键为枚举类型 #

直接把遍历得到的字符串键断言为FunnelStage类型，让TypeScript认可这个索引：

enum FunnelStage {
    LOGIN
}

const overall = {
    [FunnelStage.LOGIN]: {count: 1}
}
// 修正大小写错误
overall[FunnelStage.LOGIN].count = 2

for (let funnelStage in overall) {
    console.log(overall[funnelStage as FunnelStage].count)
}

方法二：使用Object.entries并断言类型 #

通过Object.entries直接获取键值对，同时断言整个数组的类型，避免单独处理索引：

enum FunnelStage {
    LOGIN
}

const overall = {
    [FunnelStage.LOGIN]: {count: 1}
}
overall[FunnelStage.LOGIN].count = 2

for (const [stage, data] of Object.entries(overall) as Array<[FunnelStage, { count: number }]>) {
    console.log(data.count)
}

方法三：明确对象类型后遍历枚举键 #

先给overall指定Record<FunnelStage, { count: number }>类型，再把Object.keys的结果转为枚举数组遍历：

enum FunnelStage {
    LOGIN
}

// 明确对象类型
const overall: Record<FunnelStage, { count: number }> = {
    [FunnelStage.LOGIN]: {count: 1}
}
overall[FunnelStage.LOGIN].count = 2

// 将Object.keys结果断言为枚举成员数组
for (const stage of Object.keys(overall) as Array<FunnelStage>) {
    console.log(overall[stage].count)
}

内容的提问来源于stack exchange，提问作者mp3por