Removing Currency Symbol and Replacing Comma With Point Using Pure JavaScript

How to replace comma with a dot in the number (or any replacement)

As replace() creates/returns a new string rather than modifying the original (tt), you need to set the variable (tt) equal to the new string returned from the replace function.

tt = tt.replace(/,/g, '.')

JSFiddle

How do I separate a currency symbol from a money value and preserve decimals and commas?

This should do the trick for you. The regular expression /^(\D*)(.*)/ looks for all non-digit characters at the front of the string and saves it in the first matching group and then puts the remainder of the string in the second matching group.

const regex = /^(\D*)(.*)/;

function x() {
    displayAmount = 1234.56789
    currencyFormatted = displayAmount.toLocaleString('en-US', {style: 'currency', currency: 'USD'});


    m = regex.exec(currencyFormatted );
    myElement.innerHTML = "<span>" + m[1] + "</span> " + m[2];
}

Remove currency symbol from string and convert to a number using a single line in Javascript

If the currency symbol will always be there, just use substring:

var priceNum = parseFloat(price.substring(1));

If it may or may not be there, you could use replace to remove it:

var priceNum = parseFloat(price.replace(/£/g, ""));

Beware that parseFloat("") is 0. If you don't want 0 for an empty input string, you'll need to handle that. This answer has a rundown of the various way to convert strings to numbers in JavaScript and what they do in various situations.

Side note: Using JavaScript's standard numbers for currency information is generally not best practice, because if things like the classic 0.1 + 0.2 issue (the result is 0.30000000000000004, not 0.3). There are various libraries to help, and BigInt is coming to JavaScript as well (it's a Stage 3 proposal at the moment, currently shipping in Chrome). BigInt is useful because you can use multiples of your basic currency (for instance, * 100 for pounds and pence).

unable to remove comma with "replace" in javascript

The problem is because you're only using the result of the second replace() call - you don't use the value created after you make the first replacement to remove the , characters.

That being said you can improve the logic by making a single replace() call which finds any character that isn't a digit or . and removes it. Then the formatting function will work fine. Try this:

$("#bob").blur(function() {  var numberStripped = $("#bob").val().replace(/[^\d.]/g, '');  var currencyValue = parseFloat(numberStripped).toLocaleString('en-US', {    style: 'currency',    currency: 'USD',    minimumFractionDigits: 2,    maximumFractionDigits: 2  });  $('#bob').val(currencyValue);});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script><input type="text" name="CurrencyTest" id="bob" maxlength="15">

How to format numbers as currency strings

Ok, based on what you said, I'm using this:

var DecimalSeparator = Number("1.2").toLocaleString().substr(1,1);

var AmountWithCommas = Amount.toLocaleString();
var arParts = String(AmountWithCommas).split(DecimalSeparator);
var intPart = arParts[0];
var decPart = (arParts.length > 1 ? arParts[1] : '');
decPart = (decPart + '00').substr(0,2);

return '£ ' + intPart + DecimalSeparator + decPart;

I'm open to improvement suggestions (I'd prefer not to include YUI just to do this :-) )

I already know I should be detecting the "." instead of just using it as the decimal separator...

How can I parse a string with a comma thousand separator to a number?

Yes remove the commas:

let output = parseFloat("2,299.00".replace(/,/g, ''));
console.log(output);

With a browser, how do I know which decimal separator does the operating system use?

Here is a simple JavaScript function that will return this information. Tested in Firefox, IE6, and IE7. I had to close and restart my browser in between every change to the setting under Control Panel / Regional and Language Options / Regional Options / Customize. However, it picked up not only the comma and period, but also oddball custom things, like the letter "a".

function whatDecimalSeparator() {
    var n = 1.1;
    n = n.toLocaleString().substring(1, 2);
    return n;
}

function whatDecimalSeparator() {    var n = 1.1;    n = n.toLocaleString().substring(1, 2);    return n;}
console.log('You use "' + whatDecimalSeparator() + '" as Decimal seprator');

Strip all non-numeric characters from string in JavaScript

Use the string's .replace method with a regex of \D, which is a shorthand character class that matches all non-digits:

myString = myString.replace(/\D/g,'');