Is there a way to reverse the formatting by Intl.NumberFormat in JavaScript

Question

The Intl.NumberFormat (see Mozilla's doc) provides a nice way in Javascript to format numbers into a current locale`s version like this:

new Intl.NumberFormat().format(3400); // returns "3.400" for German locale

But I couldn't find a way to reverse this formatting. Is there something like

new Intl.NumberFormat().unformat("3.400"); // returns 3400 for German locale

Thanks for any help.

Answer 1

I have found a workaround:

/**
 * Parse a localized number to a float.
 * @param {string} stringNumber - the localized number
 * @param {string} locale - [optional] the locale that the number is represented in. Omit this parameter to use the current locale.
 */
function parseLocaleNumber(stringNumber, locale) {
    var thousandSeparator = Intl.NumberFormat(locale).format(11111).replace(/\p{Number}/gu, '');
    var decimalSeparator = Intl.NumberFormat(locale).format(1.1).replace(/\p{Number}/gu, '');

    return parseFloat(stringNumber
        .replace(new RegExp('\\' + thousandSeparator, 'g'), '')
        .replace(new RegExp('\\' + decimalSeparator), '.')
    );
}

Using it like this:

parseLocaleNumber('3.400,5', 'de');
parseLocaleNumber('3.400,5'); // or if you have German locale settings
// results in: 3400.5

Not the nicest solution but it works :-)

If anyone knows a better way of achieving this, feel free to post your answer.

Update

• Wrapped in a complete reusable function
• Using the regex class \p{Number} to extract the separator. So that it also works with non-arabic digits.
• Using number with 5 places to support languages where numbers are separated at every fourth digit.

Answer 2

Here I have created a function for Reverse of format() function. This function will support reverse formatting in all locales.

function reverseFormatNumber(val,locale){
        var group = new Intl.NumberFormat(locale).format(1111).replace(/1/g, '');
        var decimal = new Intl.NumberFormat(locale).format(1.1).replace(/1/g, '');
        var reversedVal = val.replace(new RegExp('\\' + group, 'g'), '');
        reversedVal = reversedVal.replace(new RegExp('\\' + decimal, 'g'), '.');
        return Number.isNaN(reversedVal)?0:reversedVal;
    }

console.log(reverseFormatNumber('1,234.56','en'));
console.log(reverseFormatNumber('1.234,56','de'));

Answer 3

I just solved it using group replacers

const exp = /^\w{0,3}\W?\s?(\d+)[.,](\d+)?,?(\d+)?$/g
const replacer = (f, group1, group2, group3) => {
return group3 ? 
            `${group1}${group2}.${group3}` : 
            `${group1}.${group2}`
}


const usd = '$10.15'.replace(exp, replacer)
// 10.15

const eu = '€01.25'.replace(exp, replacer)
// 1.25

const brl = 'R$ 14.000,32'.replace(exp, replacer)
// 14000.32

const tai = 'TAI 50.230,32'.replace(exp, replacer)
// 50230.32


// just to test!
const el = document.getElementById('output')

const reverseUSD = new Intl.NumberFormat('en-us', { style: 'currency', currency: 'USD' }).format(usd)

el.innerHTML += `<br> from: ${reverseUSD} to ${parseFloat(usd)}`

const reverseBRL = new Intl.NumberFormat('pt-br', { style: 'currency', currency: 'BRL' }).format(brl)

el.innerHTML += `<br> from: ${reverseBRL} to ${parseFloat(brl)}`

const reverseTAI = new Intl.NumberFormat('en-us', { style: 'currency', currency: 'TAI' }).format(tai)

el.innerHTML += `<br> from: ${reverseTAI} to ${parseFloat(tai)}`

const reverseEU = new Intl.NumberFormat('eur', { style: 'currency', currency: 'EUR' }).format(eu)

el.innerHTML += `<br> from: ${reverseEU} to ${parseFloat(eu)}`

<output id=output></output>