有没有办法放松 TypeScript 编译器警告 TS2339？

Question

I am using the TypeScript compiler to check my JavaScript code as well. The reason for this is to find possible defects as early as possible. One of the compiler warnings of the TypeScript compiler is TS2339. It checks whether a type has defined a certain property. Since this can easily go wrong in JavaScript, this is a valuable compiler warning. For instance, suppose I have the following type:

mycar = {

  color: "green",

  topspeed: 180

};

and I am using somewhere in my code

c = mycar.colour;

I will get a warning that "colour" doesn't exist (typo). This would have gone unnoticed if I didn't have run the TypeScript compiler. So far so good.

But suppose you have the following JavaScript code, which is a common way of doing things in JavaScript:

mycar = {};

mycar.color = "green";

mycar.topspeed = 180;

If you run the TypeScript compiler then you will get

error TS2339: Property 'color' does not exist on type 'mycar'

Strictly speaking the TypeScript compiler is right, but actually nothing can go wrong here. You might argue why I didn't write the code as the first example, but this is not common in JavaScript and moreover in reality these data structures are far more complicated and in such a case the latter way of coding is regarded as more convenient.

So my question is: is there a possibility to relax the TypeScript compiler warning TS2339 to only spot the real issues?

Answer 1

I think this chapter of wonderful Typescript book by Basarat might answer your question better than I am. It is quite short and 100% on point

https://basarat.gitbook.io/typescript/main-1/lazyobjectliteralinitialization

Answer 2

How is Typescript supposed to know where the real issues are and which you know of ? It actually works the other way round, you can tell typescript at which places it should not safeguard you:

  mycar = {} as any;

Or you could also work with the compiler and properly type the variable:

  let mycar: { color: number, /*...*/ };