(Built-in) way in JavaScript to check if a string is a valid number

Question

I\'m hoping there\'s something in the same conceptual space as the old VB6 IsNumeric() function?

Answer 1

The accepted answer for this question has quite a few flaws (as highlighted by couple of other users). This is one of the easiest & proven way to approach it in javascript:

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

Below are some good test cases:

console.log(isNumeric(12345678912345678912)); // true
console.log(isNumeric('2 '));                 // true
console.log(isNumeric('-32.2 '));             // true
console.log(isNumeric(-32.2));                // true
console.log(isNumeric(undefined));            // false

// the accepted answer fails at these tests:
console.log(isNumeric(''));                   // false
console.log(isNumeric(null));                 // false
console.log(isNumeric([]));                   // false