noUnreachableSuper

Diagnostic Category: lint/correctness/noUnreachableSuper

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: no-this-before-super

Description

Ensures the super() constructor is called exactly once on every code path in a class constructor before this is accessed if the class has a superclass

Examples

Invalid

class A extends B {
    constructor() {}
}

code-block.js:2:5 lint/correctness/noUnreachableSuper ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This constructor has code paths that return without calling </span><span style="color: Tomato;"><strong>super()</strong></span><span style="color: Tomato;">.
  
    1 │ class A extends B {
  > 2 │     constructor() {}
      │     ^^^^^^^^^^^^^^^^
    3 │ }
    4 │ 
  
  ℹ If this is intentional, add an explicit throw statement in unsupported paths.

class A extends B {
    constructor(value) {
        this.prop = value;
        super();
    }
}

code-block.js:2:5 lint/correctness/noUnreachableSuper ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This constructor has code paths accessing </span><span style="color: Tomato;"><strong>this</strong></span><span style="color: Tomato;"> without calling </span><span style="color: Tomato;"><strong>super()</strong></span><span style="color: Tomato;"> first.
  
    1 │ class A extends B {
  > 2 │     constructor(value) {
      │     ^^^^^^^^^^^^^^^^^^^^
  > 3 │         this.prop = value;
  > 4 │         super();
  > 5 │     }
      │     ^
    6 │ }
    7 │ 
  
  ℹ </span><span style="color: lightgreen;"><strong>this</strong></span><span style="color: lightgreen;"> is accessed here:
  
    1 │ class A extends B {
    2 │     constructor(value) {
  > 3 │         this.prop = value;
      │         ^^^^
    4 │         super();
    5 │     }
  
  ℹ If this is intentional, add an explicit throw statement in unsupported paths.

class A extends B {
    constructor(cond) {
        if(cond) {
            super();
        }
    }
}

code-block.js:2:5 lint/correctness/noUnreachableSuper ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This constructor has code paths that return without calling </span><span style="color: Tomato;"><strong>super()</strong></span><span style="color: Tomato;">.
  
    1 │ class A extends B {
  > 2 │     constructor(cond) {
      │     ^^^^^^^^^^^^^^^^^^^
  > 3 │         if(cond) {
  > 4 │             super();
  > 5 │         }
  > 6 │     }
      │     ^
    7 │ }
    8 │ 
  
  ℹ If this is intentional, add an explicit throw statement in unsupported paths.

Valid

export default class A extends B {
    constructor() {
        super();
    }
}

export class A {
    constructor() {}
}

How to configure

{
  "linter": {
    "rules": {
      "correctness": {
        "noUnreachableSuper": "error"
      }
    }
  }
}