Sometimes, we want to add a class type check in TypeScript.
In this article, we’ll look at how to add a class type check in TypeScript.
How to add a class type check in TypeScript?
To add a class type check in TypeScript, we can create a function to do the check.
For instance, we write
const isFish = (pet: Fish | Bird): pet is Fish => {
return (<Fish>pet).swim !== undefined;
};
if (isFish(pet)) {
pet.swim();
} else {
pet.fly();
}
to create the isFish function that returns the pet is Fish type.
And we check if pet is a Fish by checking if the swim property isn’t undefined.
Then we call isFish with pet to check if pet is a Fish.
And then we call swim if it is a Fish.
Conclusion
To add a class type check in TypeScript, we can create a function to do the check.
