打字稿"The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or

Question

我有一个带有接口的对象数组

interface Item {
country: string;
cases: number;
deaths: number;
population: number;
}

我想制作分拣功能

const sortDescending = (type: keyof Item): void => {
data.sort((a, b) => {

return a[type] - b[type];
});

};

打字脚本不允许我执行它的问题，因为"；算术运算的左侧必须是"any"、"number"、"bigint"或枚举类型"；我知道对象中有字符串，不能用它们进行算术运算。如何修复？

Answer 1

Typescript让我们在使用算术时更加深思熟虑，如果乍一看不符合逻辑，就会抛出错误。

const sortDescending = (type: keyof Item): void => {
data.sort((a, b) => {
// add types 'as any' -> or a better type like number | boolean
return (a[type] as any) - (b[type] as any);
// (<any>a[type]) can also be an option
});
};