How to declare a function throws an error in TypeScript
- Admin
- Oct 3, 2023
- Typescript
In Programming, Error is a common requirement to handle inside a code.
Handling error is a programmer’s responsibility to have clean code and avoid the graceful exit of an application.
The typescript compiler catches the compile-time errors with type safety.
How can you handle runtime errors in typescript.?
It provides an Error
object to indicate that an error occurred.
In Typescript, the Error object is a Runtime exception or error. Currently, Typescript supports never type which supports any type of data.
In Typescript error handling using try and catch
try {
throw new Error("error is thrown");
}
catch (e){
console.log((e.message);
}
How do you declare a function which throws Error?
Unlike other programming languages as seen below, This is not supported to function throwing an error. With current version typescript(4.3.x), it is not valid
function myfunction(param:string): throws Error{
}
You can write as using never and union operator
function myfunction(test: string): string | never {
if (!test) {
throw new Error();
}
return string;
}
The above function possibility of throwing an error as well as a string.
You can combine the never
type with boolean
or number
using the union
pipe operator.