What's the most concise way to check for an integer or float in JavaScript?

Question

I want a concise expression to tell me if a given value is an integer or float. When provided the input value NaN or Infinity, I want the output value to be false, so this rules out simply checking whether typeof(val) == 'number'

Desired input / output:

• 1 => true
• -42 => true
• 3.14 => true
• NaN => false
• Infinity => false
• null => false
• undefined => false

isFinite() is almost perfect, but there's one gotcha: isFinite(null) returns true, when I actually want it to return false.

Short of always checking if ((val != nul) && isFinite(val)), is there another more concise technique?

Answer 1

// As suggested in the comments, a function:
var isNumber = function (val) {return !isNaN(parseInt(val))};
console.log(isNumber(1)) // true
console.log(isNumber(-42)) // true
console.log(isNumber(3.14)) // true
console.log(isNumber(NaN)) // false
console.log(isNumber(Infinity)) // false
console.log(isNumber(null)) // false
console.log(isNumber(undefined)) // false