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useSingleVarDeclarator (since v1.0.0)

Diagnostic Category: lint/style/useSingleVarDeclarator

Sources:

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

Section titled Examples

Invalid

Section titled 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

Section titled Valid
const foo = 0;
let bar;
let baz;
for (let i = 0, x = 1; i < arr.length; i++) {}
Section titled Related links