I haven't used typescript much but it's surprising to me that you can pass a `const` value to as an argument which is not `ReadOnly`. Does `const` not really mean anything?
‘const’ declares a variable with an immutable reference, not an immutable value. If you’re referencing a simple literal like a string or a number that’s effectively the same thing but for objects (and arrays under the hood of JavaScript are fancy objects) while the reference to your given object is constant, the properties of that objects are still mutable.
const foo = [];
foo.push(1,2,3);In practice, functions, numbers, bigint, symbols, booleans, strings, regex literals, null, and undefined are all immutable. Since you can't change the value, a const to one of these guarantees the value will never be modified.
Objects, arrays (actually just objects with a different constructor), maps, sets, TypedArrays (real arrays), etc are different. You can be guaranteed that you will be pointing to the same object instance because there's no way to swap out data at a location in memory like there is in low-level languages (yay GCs). The entries inside the hashmap or array can be modified though.
Calling `Object.freeze()` will lock down an array or object with some caveats. Sub-objects will still be modifiable (though you could recursively freeze) and this doesn't work for Map or Set (their properties like get/set/forEach will be frozen, but not the actual data) and it will throw if used on a typed array.