How to validate user input of currency - reactjs

Question

So I currently developing a website that support many languages. I have an input box where user can input the amount of currency inside. I need a function to validate if that input is legit or not.
however, because different countries use different format of number.
for example: England use '.' for decimal and ',' for thousand separator .
Where as Germany use ',' for decimal and '.' for thousand separator.
French use ',' for decimal and (space) for thousand separator...
And for Chinese/Jap , they even dont use number "1-9" to describe number
I can make a very big if-else function to do the validate base on the language they are using. something like this
number = userinput()
if "de":
return deValidator(number)
if "fr":
return frValidator(number)
if "en":
return enValidator(number)
if "zh":
return zhValidator(number)
However, is there any wiser way to do it?? what I am looking for is something like a already-built validator/library or an easier approach to solve this problem without having to writing different validator for different language

Answer 1

You can leverage on toLocaleString() method to help to build a validator; The toLocaleString() method returns a string with a language sensitive representation of the number.
const number = 123456.789;
// German uses comma as decimal separator and period for thousands
console.log(number.toLocaleString('de-DE'));
// → 123.456,789
// Arabic in most Arabic speaking countries uses Eastern Arabic digits
console.log(number.toLocaleString('ar-EG'));
// → ١٢٣٤٥٦٫٧٨٩
// India uses thousands/lakh/crore separators
console.log(number.toLocaleString('en-IN'));
// → 1,23,456.789
// the nu extension key requests a numbering system, e.g. Chinese decimal
console.log(number.toLocaleString('zh-Hans-CN-u-nu-hanidec'));
// → 一二三,四五六.七八九
// when requesting a language that may not be supported, such as
// Balinese, include a fallback language, in this case Indonesian
console.log(number.toLocaleString(['ban', 'id']));
// → 123.456,789
With this method, you can also format numbers with currency information:
const number = 10000000;
number.toLocaleString('it-IT', {style: 'currency', currency: 'EUR'})
// → 10.000.000,00 €
number.toLocaleString('it-IT', {style: 'currency', currency: 'USD'})
// → 10.000.000,00 US$
number.toLocaleString('en-US', {style: 'currency', currency: 'EUR'})
// → €10,000,000.00
number.toLocaleString('en-US', {style: 'currency', currency: 'USD'})
// → $10,000,000.00
For more details: toLocaleString https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString