parseInt is one of the oldest parts of JavaScript, so it's likely that this
is because it is (a generalisation of) the same behaviour as atoi in the C
standard library, which I guess means you'd have to ask Ken Thompson. My
guess would be because it made it possible to parse an integer out of a
longer string without copying.
The reason you're getting NaN for parseInt("1234fg",37) and
parseInt("1234fg",1) is not because of an invalid string, but an invalid
radix. Specifically, only radices of 2-26 are allowed, and the function is
specced to return NaN otherwise:
[image: 2019-11-06-151320_288x53_scrot.png]
- Leszek
On Wed, Nov 6, 2019 at 3:05 PM <[email protected]> wrote:
> Thanks for your response. I guess I didn't phrase my question not
> appropriately. I am actually curious why JavaScript does not return NaN for
> invalid inputs? Since the name of the method contains "parse", I assume it
> would throw some parsing error if the inputs are invalid.
>
> On Tuesday, October 15, 2019 at 12:20:18 PM UTC+2, [email protected]
> wrote:
>>
>> As the title says, is it a bug or is it implemented this way
>> intentionally? If the latter, I don't understand why a valid number should
>> be returned.
>> Another mysterious behavior is parseInt("1234fg",37) and
>> parseInt("1234fg",1) returns NaN as expected, but parseInt("1234fg",0)
>> returns 1234...
>>
>>
>> --
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