Implementing Short-Circuit Evaluation for Efficient JavaScript Code

{
  "title": "Implementing Short-Circuit Evaluation for Efficient JavaScript Code",
  "description": "Guidelines on using short-circuit evaluation to simplify code and avoid unnecessary operations in JavaScript.",
  "category": "JavaScript Cursor Rules",
  "rules": [
    {
      "id": "JS-SHORT-CIRCUIT-001",
      "name": "Use Logical AND (&&) for Conditional Execution",
      "description": "Utilize the logical AND operator to execute code only when a condition is truthy, reducing the need for explicit if statements.",
      "examples": {
        "good": [
          "user.isAuthenticated && displayUserProfile(user);"
        ],
        "bad": [
          "if (user.isAuthenticated) {\n  displayUserProfile(user);\n}"
        ]
      }
    },
    {
      "id": "JS-SHORT-CIRCUIT-002",
      "name": "Use Logical OR (||) for Default Values",
      "description": "Employ the logical OR operator to assign default values when a variable is falsy, streamlining variable initialization.",
      "examples": {
        "good": [
          "const username = inputName || 'Guest';"
        ],
        "bad": [
          "const username = inputName ? inputName : 'Guest';"
        ]
      }
    },
    {
      "id": "JS-SHORT-CIRCUIT-003",
      "name": "Use Nullish Coalescing Operator (??) for Null or Undefined Checks",
      "description": "Apply the nullish coalescing operator to provide default values only when a variable is null or undefined, preserving other falsy values.",
      "examples": {
        "good": [
          "const count = userInput ?? 0;"
        ],
        "bad": [
          "const count = userInput || 0;"
        ]
      }
    },
    {
      "id": "JS-SHORT-CIRCUIT-004",
      "name": "Use Optional Chaining (?.) for Safe Property Access",
      "description": "Utilize optional chaining to access nested object properties safely, preventing errors when intermediate properties are null or undefined.",
      "examples": {
        "good": [
          "const city = user?.address?.city;"
        ],
        "bad": [
          "const city = user && user.address && user.address.city;"
        ]
      }
    },
    {
      "id": "JS-SHORT-CIRCUIT-005",
      "name": "Use Logical Assignment Operators for Concise Assignments",
      "description": "Leverage logical assignment operators (||=, &&=, ??=) to simplify variable assignments based on their current value.",
      "examples": {
        "good": [
          "let config = {};\nconfig.settings ||= defaultSettings;"
        ],
        "bad": [
          "let config = {};\nif (!config.settings) {\n  config.settings = defaultSettings;\n}"
        ]
      }
    }
  ]
}