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noUselessLoneBlockStatements (since v1.3.3)

Diagnostic Category: lint/complexity/noUselessLoneBlockStatements

Sources:

Disallow unnecessary nested block statements.

In JavaScript, prior to ES6, standalone code blocks delimited by curly braces do not create a new scope and have no use. In ES6, code blocks may create a new scope if a block-level binding (let and const), a class declaration or a function declaration (in strict mode) are present. A block is not considered redundant in these cases.

Examples

Section titled Examples

Invalid

Section titled Invalid
{}
code-block.js:1:1 lint/complexity/noUselessLoneBlockStatements ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This block statement doesn't serve any purpose and can be safely removed.
  
  > 1 │ {}
      │ ^^
    2 │ 
  
  ℹ Standalone block statements without any block-level declarations are redundant in JavaScript and can be removed to simplify the code.
  

if (foo) {
  bar();
  {
    baz();
  }
}
code-block.js:3:3 lint/complexity/noUselessLoneBlockStatements  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This block statement doesn't serve any purpose and can be safely removed.
  
    1 │ if (foo) {
    2 │   bar();
  > 3 │   {
      │   ^
  > 4 │     baz();
  > 5 │   }
      │   ^
    6 │ }
    7 │ 
  
  ℹ Standalone block statements without any block-level declarations are redundant in JavaScript and can be removed to simplify the code.
  
  ℹ Safe fix: Remove redundant block.
  
    1 1 │   if (foo) {
    2 2 │     bar();
    3   │ - ··{
    4 3 │       baz();
    5   │ - ··}
    6 4 │   }
    7 5 │

Valid

Section titled Valid
while (foo) {
  bar();
}
Section titled Related links