eslint-plugin-no-boolean-switch

Adds eslint rules to disallow using boolean literals as switch statement arguments

Necessity

You should avoid such constructions, because they contain logical errors

const x = 1;

switch (true) {
  case !!x:
    console.log('logging first case');
    break;
  case x === 1:
    console.log('logging second case');
    break;
}

Let's use an example to see how switch(true) can be rewritten more safely

Was:

function getNodeDescriptionSwitch(node: Node) { 
  switch (true) { 
    case isArrayLiteralExpression(node): 
    case isObjectLiteralExpression(node): 
      return "Array or object"; 
    case isBigIntLiteral(node): 
    case isNumericLiteral(node): 
      return "Numberish"; 
    case isNoSubstitutionTemplateLiteral(node): 
    case isRegularExpressionLiteral(node): 
    case isStringLiteral(node): 
    case isTemplateLiteral(node): 
      return "Stringlike"; 
    default: 
      return "Some sort of node"; 
  } 
}

Became:

function getNodeDescriptionSwitch(node) {
  if (isArrayLiteralExpression(node) || isObjectLiteralExpression(node)) {
    return "Array or object";
  } else if (isBigIntLiteral(node) || isNumericLiteral(node)) {
    return "Numberish";
  } else if (
    isNoSubstitutionTemplateLiteral(node) ||
    isRegularExpressionLiteral(node) ||
    isStringLiteral(node) ||
    isTemplateLiteral(node)
  ) {
    return "Stringlike";
  } else {
    return "Some sort of node";
  }
}

Installation

npm i -D eslint-plugin-no-boolean-switch

Usage

Add no-switch-boolean to your .eslintrc configuration.

{
  "plugins": ["no-boolean-switch"]
}

{
  "rules": {
    "no-boolean-switch/no-boolean-switch": "warn"
  }
}

Changelog

0.1.2

• Adding installation and usage example to Readme.md

0.1.1

• Delete eslint package from peerDependencies
• Added the correct readme.md
• Set the package version to the semantically correct one

0.0.1

• Initial Release