Object 可能是“未定义”。 在数组过滤器中

Question

I´m getting Object is possibly 'undefined' trying to use filter.

interface Person {
    name: string;
    age: number;
    phone?: string;
}

let a: Person[] = [{name: "ASHLEE", age: 29},{name: "Brad", age: 32}]

const b = a.filter((item) =>
        item.phone.toLowerCase());

console.log(b);

How to solve this problem? What am I doing wrong? Thanks!

Answer 1

I am not sure what you are trying to accomplish here. To filter the Persons array you can do the following, no need to lower case it.

interface Person {
    name: string;
    age: number;
    phone?: string;
}

let a: Person[] = [{name: "ASHLEE", age: 29},{name: "Brad", age: 32}]

const b = a.filter((item) =>
        item.phone);

console.log(b);

If you are trying to lowercase phone you can apply a map function on the result.

const b = a.filter((item) =>
        item.phone).map(item => ({...item, phone: item.phone?.toLocaleLowerCase()}))

Playground link.