TypeScript’s quirks: How inconsistencies make the language more complex

Re:TypeScript’s quirks: How inconsistencies make the languag... by felixfbecker on Friday January 31, 2020 @06:28PM (#22207058)

Casting can hide errors. It's better to assign it to a variable first that has a type declaration.

    const dog: Dog = {
        breed: "Airedale",
        age: 3
    }
    printDog(dog)

An IIFE is safe too:

    printDog(((): Dog => ({
        breed: "Airedale",
        age: 3
    })())

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Re:TypeScript’s quirks: How inconsistencies make the languag... by johnghanks on Friday January 31, 2020 @11:12PM (#22208606)

I would absolutely reject a PR with the IIFE.

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Re:TypeScript’s quirks: How inconsistencies make the languag... by jahewson on Saturday February 01, 2020 @12:09AM (#22208828)

Actually this cast is safe in TypeScript, additional variables are unnecessary.

The statement ‘const d: Dog’ and the expression ‘d as Dog’ are equivalent w.r.t. type safety. The compiler will error in both cases the if the value is not a Dog.

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Re:TypeScript’s quirks: How inconsistencies make the languag... by agentcooper on Saturday February 01, 2020 @06:56AM (#22210048)

This is not correct. Following example is valid in strict TypeScript:

  interface Dog {
    breed: string;
  }
  const dog = {} as Dog;
  console.log(dog.breed);

Using `as` is very unsafe in TypeScript.

I've collected more quirks of `as` in this playground: https://www.typescriptlang.org/play/index.html#code/PTAEAMEs...

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Re:TypeScript’s quirks: How inconsistencies make the languag... by BigJono on Friday January 31, 2020 @09:14PM (#22208101)

Yeah and both of those are less readable, and used everywhere add up to a really crap code base relative to the same code in plain JS.

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Re:TypeScript’s quirks: How inconsistencies make the languag... by horseman on Friday January 31, 2020 @09:29PM (#22208180)

Yah, pojs is so much nicer because when you mistype breed as bred you get to debug the issue at runtime for a while changing things that are irrelevant when TS could have told you immediately

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