check if something is a number, in a function with an if statement

Question

I want a function to take two parameters, and if they are both numbers to tell me which is bigger. i also want it to give a nice output if they are some of them are not numbers (beacause it won't be able to calculate it anyway).

I've got to the point where it is able to handle int, but not floats. it got over my head and I'm wondering what would be the best practice to write that down.

here is what I got so far;

var iamanumbergenius = function(a, b) {
if (Number.isInteger(a) && Number.isInteger(b)) {
if (a > b) {
  console.log('first is greater');
  } else if (b > a) {
  console.log('second is greater');
  } else {
  console.log('equality is the answer');
  }
} else { console.log('i only like nums'); }
}

sorry for ugly code, brought right out of chrome dev tools, where there's no such thing as hitting the enter with out anxiety XD

pretty sure I'm missing some method or typeof thing... maybe with some more boolean operatos and also number.isfloat? in that case I'm not sure what comes before what in term of order of operations: || and the &&..

thanks! I'm really new to that stuff so any help would be great :)

If the `a` and `b` are already numbers, `typeof a === 'number'` would return true for integers or floats. — Taplar, Jan 16 '19 at 23:25
`typeof value == 'number'` tends to work pretty well. Noting that *NaN* is type number too. `value % 1 === 0` also works for integer. — RobG, Jan 16 '19 at 23:27
try isNaN() to check if is a number and not if it's only an integer. — Manuel Espinosa, Jan 16 '19 at 23:27
Do you want to check for numbers or integers only? Because the title tells numbers but code example integers. — Bernhard, Jan 16 '19 at 23:27
@Taplar thanks! turned out I have simply forgotten to put the ''... silly 01:30 me — gon buzaglo, Jan 16 '19 at 23:29

Jack Bashford · Answer 1 · 2019-01-16T23:33:27.233

1

Because typeof returns number for both integers and floats, you can use that for your function.

Demonstration of typeof:

console.log(typeof 1.3);

Here's how you implement it in your function:

if (typeof a === 'number' && typeof b === 'number')

Also, because typeof NaN === 'number', you should useisNaN()in yourif` statement too:

if (typeof a === 'number' && typeof b === 'number' && !(isNaN(a) || isNaN(b)))

edited Jan 16 '19 at 23:33

answered Jan 16 '19 at 23:28

Jack Bashford

43,180
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50
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Note that `typeof NaN == 'number'`. – RobG Jan 16 '19 at 23:29
Good point @RobG, I'll include `isNaN()` as well. Thanks for picking up on that. – Jack Bashford Jan 16 '19 at 23:30

score 0 · Answer 2 · answered Jan 16 '19 at 23:31

0

Try this:

console.log(isNaN(123));
console.log(isNaN(1.23));
console.log(isNaN('stack'));

answered Jan 16 '19 at 23:31

Manuel Espinosa

108
12

check if something is a number, in a function with an if statement

2 Answers2