How can I parse a string with a comma thousand separator to a number?
On modern browsers you can use the built in Intl.NumberFormat to detect the browser's number formatting and normalize the input to match.
function parseNumber(value, locales = navigator.languages) {
const example = Intl.NumberFormat(locales).format('1.1');
const cleanPattern = new RegExp(`[^-+0-9${ example.charAt( 1 ) }]`, 'g');
const cleaned = value.replace(cleanPattern, '');
const normalized = cleaned.replace(example.charAt(1), '.');
return parseFloat(normalized);
}
const corpus = {
'1.123': {
expected: 1.123,
locale: 'en-US'
},
'1,123': {
expected: 1123,
locale: 'en-US'
},
'2.123': {
expected: 2123,
locale: 'fr-FR'
},
'2,123': {
expected: 2.123,
locale: 'fr-FR'
},
}
for (const candidate in corpus) {
const {
locale,
expected
} = corpus[candidate];
const parsed = parseNumber(candidate, locale);
console.log(`${ candidate } in ${ corpus[ candidate ].locale } == ${ expected }? ${ parsed === expected }`);
}
Their's obviously room for some optimization and caching but this works reliably in all languages.
Yes remove the commas:
let output = parseFloat("2,299.00".replace(/,/g, ''));
console.log(output);
Removing commas is potentially dangerous because, as others have mentioned in the comments, many locales use a comma to mean something different (like a decimal place).
I don't know where you got your string from, but in some places in the world "2,299.00"
= 2.299
The Intl
object could have been a nice way to tackle this problem, but somehow they managed to ship the spec with only a Intl.NumberFormat.format()
API and no parse
counterpart :(
The only way to parse a string with cultural numeric characters in it to a machine recognisable number in any i18n sane way is to use a library that leverages CLDR data to cover off all possible ways of formatting number strings http://cldr.unicode.org/
The two best JS options I've come across for this so far:
- https://github.com/google/closure-library/tree/master/closure/goog/i18n
- https://github.com/globalizejs/globalize