在自定义类型上使用typeof键时，如何解析ts(2339)

Question

问题

这篇文章底部的TypeScript导致以下错误：

类型"｛title：string；outline："上不存在属性"push"一串为什么：字符串；additional:string；｝'。ts(2339(

我理解错误发生的原因，只是不知道如何解决。理想情况下，我会将idea密钥从可能的密钥列表中排除，但我不确定如何解决。

TypeScript

type Idea = {
challenges: Array<string>,
personas: Array<string>,
experiences: Array<string>,
idea: {
title: string,
outline: string,
why: string,
additional: string,
}
};
let idea:Idea = {
challenges: [],
personas: [],
experiences: [],
idea: {
title: "",
outline: "",
why: "",
additional: "",
}
};
function addtoIdea(ideaItem:string, uniqueId:string){
idea[ideaItem as keyof typeof idea].push(uniqueId);        
}
addtoIdea("challenges","abcd1234");

Answer 1

正如我的评论中所提到的，您需要首先确保您尝试push进入的属性是Array：

type Idea = {
challenges: Array<string>,
personas: Array<string>,
experiences: Array<string>,
idea: {
title: string,
outline: string,
why: string,
additional: string,
}
};
let idea:Idea = {
challenges: [],
personas: [],
experiences: [],
idea: {
title: "",
outline: "",
why: "",
additional: "",
}
};
function addtoIdea(ideaItem:string, uniqueId:string){
const prop = idea[ideaItem as keyof typeof idea]; // string[] | { ... }
if(Array.isArray(prop)){
prop.push(uniqueId); // prop is string[] 
}    
}
addtoIdea("challenges","abcd1234");

工作操场