I have a simple object having two fields name and age, initially those are defined as undefined and later in the code the value will get assigined
const s={
name:undefined,
age:undefined
}
s.name="Test" //error
when I am trying to assign any value to my attributes it gives me typescript error
Type '"Test"' is not assignable to type 'undefined'.
Can anyone explain why I am getting this error in typescript and how to fix it
You did not explicitly define a type for s, so the compiler tries to infer one, based on the provided values.
The inferred type of s is:
{
name: undefined;
age: undefined;
}
You have set an explicit type like so:
type User = {
name: string | undefined;
age: number | undefined;
};
const s: User = {
name: undefined,
age: undefined
};
s.name = "Test"; //should work
If you look at the inferred type of s you can see that it is
{
name:undefined;
age:undefined;
}
TypeScript can't infer that any other type might be allowed here because you didn't supply that info.
Create a type:
interface Person{
name: string | undefined;
age: number | undefined;
}
then declare s with this type:
const s:Person = {
name: undefined;
age: undefined;
}