如何在typescript中检查值的类型？

function printInfo(value: unknown) {
    if (typeof value === 'string') {
        console.log('It is a string:', value);
    } else if (typeof value === 'number') {
        console.log('It is a number:', value);
    } else {
        console.log('Unknown type');
    }
}

class Animal {}
class Dog extends Animal {}

function checkAnimal(animal: any) {
    if (animal instanceof Dog) {
        console.log('It is a dog');
    } else if (animal instanceof Animal) {
        console.log('It is an animal');
    } else {
        console.log('It is not an animal');
    }
}

interface Fish {
    swim: () => void;
}

interface Bird {
    fly: () => void;
}

function isFish(pet: Fish | Bird): pet is Fish {
    return (pet as Fish).swim !== undefined;
}

function move(pet: Fish | Bird) {
    if (isFish(pet)) {
        pet.swim();
    } else {
        pet.fly();
    }
}

interface Square {
    kind: 'square';
    size: number;
}

interface Rectangle {
    kind: 'rectangle';
    width: number;
    height: number;
}

type Shape = Square | Rectangle;

function area(s: Shape) {
    if ('size' in s) {
        return s.size * s.size; // s is Square here
    } else {
        return s.width * s.height; // s is Rectangle here
    }
}

function assertIsString(value: any): asserts value is string {
    if (typeof value !== 'string') {
        throw new Error('Value is not a string');
    }
}

function processString(value: unknown) {
    assertIsString(value);
    console.log(value.toUpperCase());
}