noUnreachable

Diagnostic Category: lint/correctness/noUnreachable

JavaScript (and super languages)

Since: v1.0.0

Note

• This rule is recommended by Biome. A diagnostic error will appear when linting your code.

Sources:

• Same as: no-unreachable

Description

Disallow unreachable code

Examples

Invalid

function example() {
    return;
    neverCalled();
}

code-block.js:3:5 lint/correctness/noUnreachable ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This code will never be reached …
  
    1 │ function example() {
    2 │     return;
  > 3 │     neverCalled();
      │     ^^^^^^^^^^^^^^
    4 │ }
    5 │ 
  
  ℹ … because this statement will return from the function beforehand
  
    1 │ function example() {
  > 2 │     return;
      │     ^^^^^^^
    3 │     neverCalled();
    4 │ }
  

function example() {
    for(let i = 0; i < 10; ++i) {
        break;
    }
}

code-block.js:2:28 lint/correctness/noUnreachable ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This code will never be reached …
  
    1 │ function example() {
  > 2 │     for(let i = 0; i < 10; ++i) {
      │                            ^^^
    3 │         break;
    4 │     }
  
  ℹ … because this statement will break the flow of the code beforehand
  
    1 │ function example() {
    2 │     for(let i = 0; i < 10; ++i) {
  > 3 │         break;
      │         ^^^^^^
    4 │     }
    5 │ }
  

function example() {
    for(const key in value) {
        continue;
        neverCalled();
    }
}

code-block.js:4:9 lint/correctness/noUnreachable ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This code will never be reached …
  
    2 │     for(const key in value) {
    3 │         continue;
  > 4 │         neverCalled();
      │         ^^^^^^^^^^^^^^
    5 │     }
    6 │ }
  
  ℹ … because this statement will continue the loop beforehand
  
    1 │ function example() {
    2 │     for(const key in value) {
  > 3 │         continue;
      │         ^^^^^^^^^
    4 │         neverCalled();
    5 │     }
  

How to configure

biome.json

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

Related links

• Disable a rule
• Configure the rule fix
• Rule options