Unnecessary Default Constructor

javascript.unnecessary_default_constructor

Severity

low

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Code Smell

Language

JavaScript

Description

Reports class constructors that the engine would already insert implicitly:

An empty constructor on a class without an extends clause.
A derived class constructor whose body is a single super(…) call that just forwards every parameter to the superclass.

In either case the explicit constructor adds no behaviour and is just noise.

Rationale

JavaScript automatically generates a constructor when a class declares none — constructor() {} for non-derived classes, and constructor(…args) { super(…args); } for derived classes. Writing the same constructor by hand:

Adds nothing the runtime doesn’t already do.
Bloats the source for readers and tooling.
Drifts over time — someone adds an irrelevant comment / parameter to the explicit form, others assume it has a purpose, and the class accumulates unnecessary scaffolding.

// Bad
class A {
  constructor() {}
}

class B extends Base {
  constructor(a, b) {
    super(a, b);
  }
}

class C extends Base {
  constructor(...args) {
    super(...args);
  }
}

Remediation

Remove the redundant constructor entirely. The implicit one is created automatically.

// Good
class A {}

class B extends Base {}

class C extends Base {}

If the constructor needs to do real work (initialise state, transform parameters, validate input), keep it — the rule only flags constructors that match the implicit default exactly.

References

MDN — constructor