Opinion

ts.md

Anyone have an opinion on this field assignment to this in classes?

export class App {
    foo = this.bar;
    
    constructor(public bar){
    }
}

it compiles to the same thing as:

export class App {
    foo;

    constructor(public bar){
        this.foo = bar;
    }
}

1st option and maybe I would express my intentions a little better with a getter. If foo is a computed property or is pointing at something else, I would probably do "get foo() { return this.bar; }"

2nd option IMO. Still weird, but 2nd option reads easier.

I prefer the first option.

• I don't have repeat 'foo' twice
• if I have a const initializer, then I always put it next to the field declaration. And it is nice to have all my initializers in the same place.

(2) because it's more clear what's happening. To someone from Javascript, the "this" in example (1) looks like the global scope, and it looks like a programming error.

Side issue: does bar have to be public? Will the DI work with constructor(private bar: Bar)?

https://gist.github.com/johnlindquist/5b8a1111cda507ea3d05

I don't like the argument that is essentially "someone who doesn't understand TypeScript won't understand it."

I agree with @vsavkin's points exactly.

2nd Option. Any code in property initializes actually executes before the body of the constructor. This is great because it allows you to use initialized members in the constructor body e.g.:

export class App {
    foo = [];
    constructor(public bar){
        this.foo.push(bar); // Safe to do
    }
}

So if you use the 1st option, it might not do what you think it does. e.g. What do you think is the value of foo in this case?

export class App {
    foo = this.bar;
    constructor(public bar){
        bar = bar * 2;
    }
}

Whereas with the following case there is no ambiguity:

export class App {
    foo;
    constructor(public bar){
        this.foo = bar * 2;
    }
}

I know the example is a bit contrived 🌹

Option 2 seems intuitive to me and I also agree with @basarat 's points

Option 2...but why wouldn't you just use this.bar and get rid of foo altogether?