Breaking News: Grepper is joining You.com. Read the official announcement!

typescript as operator

Marcel Tauber answered on September 26, 2022 Popularity 8/10 Helpfulness 1/10

answer typescript as operator

related typescript as operator

typescript as operator

Comment

/* 
User-Defined Type Guards
It would be much better if once we performed the check,
we could know the type of pet within each branch.

It just so happens that TypeScript has something called a type guard.
A type guard is some expression that performs a runtime check 
that guarantees the type in some scope.

Using type predicates
To define a type guard, we simply need to define a function 
whose return type is a type predicate:
*/

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

Popularity 8/10 Helpfulness 1/10 Language typescript

Source: www.typescriptlang.org

Tags: as-operator typescript

Link to this answer
Share Copy Link

Contributed on Sep 26 2022

Marcel Tauber

0 Answers Avg Quality 2/10

Closely Related Answers

typescript as operator

Comment

let pet = getSmallPet();
let fishPet = pet as Fish;
let birdPet = pet as Bird;
 
if (fishPet.swim) {
  fishPet.swim();
} else if (birdPet.fly) {
  birdPet.fly();
}
//Example of code working via property accessors, using type assertion

Popularity 8/10 Helpfulness 1/10 Language typescript

Source: www.typescriptlang.org

Tags: typescript as-operator as

Link to this answer
Share Copy Link

Contributed on Sep 26 2022

Marcel Tauber

0 Answers Avg Quality 2/10

typescript as operator

Contents

More Related Answers

typescript as operator

Closely Related Answers

typescript as operator

Grepper

Documentation

Social

Legal

Contact

Oops, You will need to install Grepper and log-in to perform this action.