LowFile-scopeJavaScript / TypeScript Plug & play

Always Use isFinite to Validate Numbers

Ensure that isFinite is used to validate numbers. Without this, NaN or Infinity can cause unexpected behavior and runtime errors.

Why this matters

Validating numbers without isFinite can lead to unexpected behavior with NaN or Infinity, which can cause runtime errors.

Side-by-side examples engineers can pattern-match during review.

Avoid

const value = Number("Not a Number");
if (value) {
  console.log("Valid number"); // Will not catch NaN or Infinity
}

Prefer

const value = Number("Not a Number");
if (isFinite(value)) {
  console.log("Valid number");
}

Bad

const value = Number("Not a Number");
if (value) {
  console.log("Valid number"); // Will not catch NaN or Infinity
}

Good

const value = Number("Not a Number");
if (isFinite(value)) {
  console.log("Valid number");
}

From the same buckets as this rule.

Critical
Avoid equality operators in loop termination conditions
Check if loops use equality operators (== or !=) in termination conditions. These can lead to infinite loops if the condition is never met exactly. Instead, use relational operators like < or > for safer loop termination.
error-handlingreadability-refactor
Critical
Avoid Returning Null in Non-Async Task Methods
Returning null from a Task or Task<T> method causes a NullReferenceException if awaited. Use Task.CompletedTask or Task.FromResult<T>(null) instead.
error-handlingreadability-refactor+1
Critical
Avoid Using Boolean Expressions in `except` Statements
Detect `except` clauses that use `or` or `and` to catch multiple exceptions. This does not work as intended. Recommend using a tuple of exceptions instead.
error-handlingstack-python