useSingleVarDeclarator

Diagnostic Category: lint/style/useSingleVarDeclarator

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: one-var

Description

Disallow multiple variable declarations in the same variable statement

In JavaScript, multiple variables can be declared within a single var, const or let declaration. It is often considered a best practice to declare every variable separately. That is what this rule enforces.

Examples

Invalid

let foo = 0, bar, baz;

code-block.js:1:1 lint/style/useSingleVarDeclarator  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Declare variables separately
  
  > 1 │ let foo = 0, bar, baz;
      │ ^^^^^^^^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Break out into multiple declarations
  
    1   │ - let·foo·=·0,·bar,·baz;
      1 │ + let·foo·=·0;
      2 │ + let·bar;
      3 │ + let·baz;
    2 4 │

Valid

const foo = 0;
let bar;
let baz;

for (let i = 0, x = 1; i < arr.length; i++) {}

How to configure

{
  "linter": {
    "rules": {
      "style": {
        "useSingleVarDeclarator": "error"
      }
    }
  }
}