Standard Library

The Standard Library
contains utilities that are functionally broken but remain for legacy reasons.

• 29.1 Use Number.isNaN instead of global isNaN.
  eslint: no-restricted-globals

  Why? The global isNaN coerces non-numbers to numbers, returning true for anything that coerces to NaN.
  If this behavior is desired, make it explicit.

  // bad
  isNaN('1.2'); // false
  isNaN('1.2.3'); // true
  // good
  Number.isNaN('1.2.3'); // false
  Number.isNaN(Number('1.2.3')); // true

• 29.2 Use Number.isFinite instead of global isFinite.
  eslint: no-restricted-globals

  Why? The global isFinite coerces non-numbers to numbers, returning true for anything that coerces to a finite number.
  If this behavior is desired, make it explicit.

  // bad
  isFinite('2e3'); // true
  // good
  Number.isFinite('2e3'); // false
  Number.isFinite(parseInt('2e3', 10)); // true