CODEWITHSUNDEEP
javascript
peter.petrov
peter.petrov

Reputation: 39437

JavaScript - conversion of "0" to number

I can understand why

10 % "test"

returns NaN... because "test" is converted to a number first which gives NaN and then any subsequent arithmetic operation involving NaN results in NaN too.

But why does 

    10 % "0"

return NaN ?

"0" is usually converted to a number as 0 e.g. in 1 * "0".

If I try 10 / "0" this gives Infinity which also makes sense.

So... why does that expression 10 % "0" return NaN ?! Any logic behind this?

Upvotes: 0

Views: 71

Answers (2)

Peter Collingridge
Peter Collingridge

Reputation: 10979

10 % 0 also returns NaN because you're asking what's the remainder when you divide by 0, and there's no meaningful answer to that.

Upvotes: 2

Christian Vincenzo Traina
Christian Vincenzo Traina

Reputation: 10384

Your guess is right, in all the number only operators, if used in strings, Javascript will try to convert them in numbers.

The same also happens with the remainder operator:

const x = "10"%"3";
console.log('10 % 3 = ' + x);

So why you get NaN evaluating 10%"0"? Well, it will be converted to 10%0, but the remainder operator has no particualr meaning if used on 0 (you can't divide by 0 in first instance). So you get NaN:

const x = 10 % 0; // numeric only operation
console.log('10 % 0 = ' + x); // NaN, the above operation has no meaning

Upvotes: 4

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