I have this code snippet in TypeScript:
const arr: ReadonlyArray<string> = [
"123",
"234"
];
arr.push("345");
TS compiler shows an error:
Property 'push' does not exist on type 'ReadonlyArray<string>'.
Of course, it's clear that I cannot change/alter this array. The question is: what is the base class for ReadonlyArray? Does it inherit from standard Array class?
https://www.typescriptlang.org/docs/handbook/interfaces.html states that:
TypeScript comes with a
ReadonlyArray<T>type that is the same asArray<T>with all mutating methods removed, so you can make sure you don’t change your arrays after creation
If you want the source, head over to:
https://github.com/Microsoft/TypeScript/blob/master/src/lib/es5.d.ts#L1121 (01.06.2022) - Search for "ReadonlyArray" if source file evolved.
(its definition is on the line 1121 in the current version).