TypeScript and dot-notation access to objects

Question

If TypeScript is a strict superset of JavaScript, why is dot notation on an arbitrary object erroneous? I have JS code that I want to convert over to TS for better type safe

Answer 1

I personally prefer to specify types whenever I have the chance.

Note, that you can only instantiate this variable with {} if you define the fields as optional with the ?: operator.

let x: {foo?: string, bar?: string} = {};
x.foo = 'foo';
x.bar = 'bar';

As others have said, if you plan to use this type multiple times, it's probably better to make an explicit class for it.

PS: it's better to use let instead of var when programming in typescript. (e.g. the scope of a var declaration is a bit quirky, compared to a let which does what you expect it to do.)