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

mwilson got there before I could! ;)

In the code above, Typescript is unable to determine that the object x exposes a property called bar so cannot resolve it when displaying Intellisense.

Instead, add foo, bar, etc. as properties of the object itself:

var x = {
    foo: "FOO",
    bar: "BAR"
};

Then, when using the Typescript Playground, you'll be see the Intellisense work as expected:

HTH