Types such as string, number, and any in Ts cannot be used as indexes, how to deal with them?

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Introduction

Types such as string, number, and any in Ts cannot be used as indexes, how to deal with them?
Error: 元素隐式具有“any”类型，因为类型为“number”的表达式不能用于索引类型“[***”。在类型“[ ***”上找不到具有类型为“number"的参数的索引签名。 ts(7053)
use of keyof

question

Types such as string, number, and any in Ts cannot be used as indexes, how to deal with them?

const handerField = (item: number) => {
    
    
   caselist= data.showList[item]//报错
}

Elements implicitly have type any, because type number cannot be used to index {} types.

Solution

method 1

const handerField = (item: number) => {
    
    
   caselist= (data.showList as any)[item];
}

Method 2

const handerField = (item: number) => {
    
    
   caselist= data.showList [item as keyof typeof data.showList ]
}

Method 3

const handerField =  function <T extends object, K extends keyof T>(obj: T, key: K) {
    
    
  return obj[key];
}