useWhile

JavaScript (and super languages)

Summary

• Rule available since: v1.0.0
• Diagnostic Category: lint/complexity/useWhile
• This rule has a safe fix.
• The default severity of this rule is warning.
• Sources:
  • Same as sonarjs/prefer-while

How to configure

biome.json

{
  "linter": {
    "rules": {
      "complexity": {
        "useWhile": "error"
      }
    }
  }
}

Description

Enforce the use of while loops instead of for loops when the initializer and update expressions are not needed.

Examples

Invalid

for (; x.running;) {
    x.step();
}

code-block.js:1:1 lint/complexity/useWhile  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Use a while loop instead of a for loop.
  
  > 1 │ for (; x.running;) {
      │ ^^^^^^^^^^^^^^^^^^
    2 │     x.step();
    3 │ }
  
  ℹ Prefer a while loop over a for loop without initialization and update.
  
  ℹ Safe fix: Use a while loop.
  
    1   │ - for·(;·x.running;)·{
      1 │ + while·(x.running)·{
    2 2 │       x.step();
    3 3 │   }
  

Valid

for (let x = 0; x < 10; i++) {}

let x = 0
for (; x < 10; i++) {}

for (let x = 0; x < 10;) {
    i++
}

Related links

• Disable a rule
• Configure the code fix
• Rule options
• Source Code
• Test Cases