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@studnicky/v8/conditional-property-assignment ​

Reports conditional establishment of this properties in a constructor or a same-class helper called directly by that constructor when the branches are not proven to establish the same property set. It covers if/else, ternaries, && assignments, Object.assign(this, condition ? {...} : {...}), and switch statements. It examines direct assignments, including one block level within a branch; computed member writes belong to dynamic-property-access.

The rule accepts a complete if/else or ternary when both alternatives assign the same property names. A bare if, an else if chain, a short-circuit assignment, a conditional Object.assign with spreads or computed keys, or different property sets cannot establish that every instance has the same shape and is reported. A switch is reported only when its cases establish more than one property name.

The distinction is about divergent maps, not dictionary mode: both branch shapes retain fast properties. Across a two-instance pool and 5,000,000 reads, a same-property branch read took 5.17 ms, while a differing-property branch took 6.75 ms (1.3×).

Fixable: No · Options: No · Suggested severity: error

✗ Incorrect ​

ts
class Connection {
  public constructor(secure: boolean) {
    if (secure) {
      this.protocol = 'https';
    } else {
      this.port = 80;
    }
  }
}
ts
class Connection {
  public constructor(secure: boolean) {
    secure && (this.protocol = 'https');
  }
}

✓ Correct ​

ts
class Connection {
  public protocol: string;

  public constructor(secure: boolean) {
    if (secure) {
      this.protocol = 'https';
    } else {
      this.protocol = 'http';
    }
  }
}
ts
class Connection {
  public protocol: string;

  public constructor(secure: boolean) {
    this.protocol = secure ? 'https' : 'http';
  }
}