@typescript-eslint/class-literal-property-style

A class can expose a constant as a readonly field or as a getter that returns a literal. From the outside, you read both the same way. This rule picks one, so every class writes it the same way. By default it's the readonly field, which is shorter.

Only literals count: strings, numbers, booleans, null, regular expressions, and templates without ${}.

Configure

Off by default. To turn it on:

[lint.rules]
"@typescript-eslint/class-literal-property-style" = "error" # or "warn"

Every option, set to its default:

[lint.rules]
# "fields" or "getters"
"@typescript-eslint/class-literal-property-style" = ["error", "fields"]

Examples

Reported:

class Server {
  get host() {
    return "localhost";
  }
}

Not reported:

class Server {
  readonly host = "localhost";

  // Not a literal.
  get url() {
    return `http://${this.host}`;
  }
}

A getter that has a setter with the same name can't become a readonly field, so the rule leaves it alone:

class Server {
  get host() {
    return "localhost";
  }
  set host(value: string) {
    console.warn("host is fixed", value);
  }
}

Options

Option	What it does
"fields" (default)	Report a getter that only returns a literal.
"getters"	Report a readonly field with a literal as its value.

class Server {
  readonly host = "localhost";
}

class Server {
  get host() {
    return "localhost";
  }
}

With "getters", a field that the constructor assigns to isn't reported:

class Server {
  readonly host = "localhost";

  constructor(host?: string) {
    if (host) this.host = host;
  }
}