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Number Static Methods

Number.isNaN()

Determine whether the passed value is NaN.

Number.isFinite()

Determine whether the passed value is a finite number.

Number.isInteger()

Determine whether the passed value is an integer.

Number.isSafeInteger()

Determine whether the passed value is a safe integer (a number between -(253 - 1) and 253 - 1).

Number.parseFloat()

Convert a string or a number to a float.

Number.parseInt()

Convert a string or a number to an integer.

Note that isNan(), isFinite(), parseFloat(), and parseInt() also exist as global functions.
<!DOCTYPE html>
<html>
<body>
<script>
  console.log(isNaN(NaN));
  console.log(Number.isNaN(NaN));

  console.log(isFinite(100));
  console.log(Number.isFinite(100));

  // console.log(isInteger(100.0));  // ReferenceError
  console.log(Number.isInteger(100.0));

  // console.log(isSafeInteger(100.0));  // ReferenceError
  console.log(Number.isSafeInteger(100.0));

  console.log(parseFloat(10));
  console.log(Number.parseFloat(10));

  console.log(parseInt("100abc123"));
  console.log(Number.parseInt(100.9));

  console.log(parseInt('10a', 2));
  console.log(parseInt('10A', 15));
</script>
</body>
</html>

function isNumeric(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
}

true true true true true true 10 10 100 100 2 235

// Here, 1/0 -> "Inifinity" -> 18nifity -> 18

<!DOCTYPE html>
<html>
<body>
<script>
  console.log(parseInt(1 / 0, 19));
</script>
</body>
</html>

18