Check if character is number?

Question

I need to check whether justPrices[i].substr(commapos+2,1).

The string is something like: \"blabla,120\"

In this case it would check whether \'0

Answer 1

The shortest solution is:

const isCharDigit = n => n < 10;

You can apply these as well:

const isCharDigit = n => Boolean(++n);

const isCharDigit = n => '/' < n && n < ':';

const isCharDigit = n => !!++n;

if you want to check more than 1 chatacter, you might use next variants

Regular Expression:

const isDigit = n => /\d+/.test(n);

Comparison:

const isDigit = n => +n == n;

Check if it is not NaN

const isDigit = n => !isNaN(n);