javascript-eslint-no-lonely-if

Normalize JavaScript-family else { if (...) ... } blocks into else if (...) ... chains when the else block contains only that nested if, matching ESLint's no-lonely-if intent without changing runtime behavior.

What It Rewrites

Before:

js
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if (cond1) {
  stmt1();
} else {
  if (cond2) {
    stmt2();
  }
}

After:

js
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if (cond1) {
  stmt1();
} else if (cond2) {
  stmt2();
}

The codemod also normalizes nested chains in one run, so else { if (...) ... else { if (...) ... } } becomes a flat else if chain.

Scope

• Targets .js, .jsx, .mjs, .cjs, .ts, and .tsx
• Preserves inner else branches
• Preserves comments around the removed else block and inner if
• Preserves multiline literal contents by keeping inner branch text intact instead of reindenting it
• Skips files under dist/**, build/**, vendor/**, and *.min.*
• Skips files containing codemod:ignore no-lonely-if by default

No-Op Cases

• else blocks with more than one non-comment statement
• else blocks whose single statement is not an if
• if statements without an else
• Code already written as else if
• Excluded or pragma-marked files
• Files with syntax errors are skipped by the codemod and reported with a diagnostic

Usage

bash
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pnpm dlx codemod@latest workflow run -w . -t /path/to/project --no-interactive

Override the ignore pragma at runtime:

bash
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pnpm dlx codemod@latest workflow run -w . -t /path/to/project --no-interactive --param ignore_pragma="custom pragma"

Development

bash
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pnpm test
pnpm dlx codemod@latest workflow validate -w .
pnpm dlx codemod@latest workflow run -w . -t /path/to/project --no-interactive

License

MIT