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noConstructorReturn (since v1.0.0)

Diagnostic Category: lint/correctness/noConstructorReturn

Sources:

Disallow returning a value from a constructor.

Returning a value from a constructor of a class is a possible error. Forbidding this pattern prevents errors resulting from unfamiliarity with JavaScript or a copy-paste error.

Only returning without a value is allowed, as it’s a control flow statement.

Examples

Section titled Examples

Invalid

Section titled Invalid
class A {
    constructor() {
        return 0;
    }
}
correctness/noConstructorReturn.js:3:9 lint/correctness/noConstructorReturn ━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ The constructor should not return a value.
  
    1 │ class A {
    2 │     constructor() {
  > 3 │         return 0;
      │         ^^^^^^^^^
    4 │     }
    5 │ }
  
  ℹ The constructor is here:
  
    1 │ class A {
  > 2 │     constructor() {
      │     ^^^^^^^^^^^^^^^
  > 3 │         return 0;
  > 4 │     }
      │     ^
    5 │ }
    6 │ 
  
  ℹ Returning a value from a constructor is ignored.

Valid

Section titled Valid
class A {
    constructor() {}
}
class B {
    constructor(x) {
        return;
    }
}
Section titled Related links