convert a JavaScript string variable to decimal/money

Question

How can we convert a JavaScript string variable to decimal?

Is there a function such as:

parseInt(document.getElementById(amtid4).innerHTML)

lonesomeday · Accepted Answer · 2020-12-28T16:36:36.840

276

Yes -- parseFloat.

parseFloat(document.getElementById(amtid4).innerHTML);

For formatting numbers, use toFixed:

var num = parseFloat(document.getElementById(amtid4).innerHTML).toFixed(2);

num is now a string with the number formatted with two decimal places.

edited Dec 28 '20 at 16:36

answered May 23 '11 at 10:16

lonesomeday

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Can we make that variable with 2 decimal points such as 120.50? right now I am getting 120.5 only. – Varada May 23 '11 at 10:27
21

To quote @PhilipWhitehouse "Please, to anyone reading this in the future, do not use float to store currency. You will loose precision and data. You should store it as a integer number of cents (or pennies etc.) and then convert prior to output.". Source: http://stackoverflow.com/questions/149055/how-can-i-format-numbers-as-money-in-javascript – SSH This Nov 27 '13 at 17:33
@SSHThis As far as I'm aware JavaScript doesn't have an integer type. It only has a Number type which are all stored internally as 64bit floating point numbers. Your point is valid for other languages that do have integer types such as C#, C++, but not really for JavaScript. – Simon Brangwin Feb 11 '15 at 04:06
1

@SimonBrangwin His point is still valid, but the semantics can be confusing. What he really means is "only store currency as whole numbers in javascript since they'll be stored as floating point numbers". – Josh Noe Aug 07 '17 at 00:21
1

Just a reminder: `parseFloat('22w')` is `22` and `parseFloat('w22')` is `NaN` – I.G. Pascual Nov 15 '17 at 11:18
First Link is broken. – pungggi Dec 27 '20 at 21:41
Thanks, @pungggi: both links now fixed. – lonesomeday Dec 28 '20 at 16:37
When I try `parseFloat("11.0")` it results in 11 instead of 11.0 – RixTheTyrunt Jul 06 '22 at 12:04
@RixTheTyrunt in what way is this not what you expect? – lonesomeday Jul 09 '22 at 10:28
It's just weird that JavaScript erases the `.0` part – RixTheTyrunt Jul 10 '22 at 12:55

KooiInc · Answer 2 · 2019-11-11T14:22:51.747

76

You can also use the Number constructor/function (no need for a radix and usable for both integers and floats):

Number('09'); /=> 9
Number('09.0987'); /=> 9.0987

Alternatively like Andy E said in the comments you can use + for conversion

+'09'; /=> 9
+'09.0987'; /=> 9.0987

edited Nov 11 '19 at 14:22

answered May 23 '11 at 10:32

KooiInc

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This isn't supported by IE11 – Pants Nov 10 '19 at 23:06

score 19 · Answer 3 · answered Nov 28 '15 at 08:34

19

var formatter = new Intl.NumberFormat("ru", {
  style: "currency",
  currency: "GBP"
});

alert( formatter.format(1234.5) ); // 1 234,5 £

https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/NumberFormat

answered Nov 28 '15 at 08:34

zloctb

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I had no idea this existed. – protometa Aug 08 '19 at 04:17
Best answer by far. parseFloat? Precision hell? No, thx! `Intl.NumberFormat` nails it. – Joshua Burns Jan 08 '20 at 02:39

score 12 · Answer 4 · edited Dec 20 '12 at 12:54

12

This works:

var num = parseFloat(document.getElementById(amtid4).innerHTML, 10).toFixed(2);

edited Dec 20 '12 at 12:54

Eitan T

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answered Dec 20 '12 at 12:33

Sanjay

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It works if the decimals are not zeros, for instance: `parseFloat('32.00').toFixed(2)` returns `32`, and not 32.00 – Mario Nezmah Feb 09 '23 at 11:16

score 2 · Answer 5 · answered Jun 29 '14 at 19:06

An easy short hand way would be to use +x It keeps the sign intact as well as the decimal numbers. The other alternative is to use parseFloat(x). Difference between parseFloat(x) and +x is for a blank string +x returns 0 where as parseFloat(x) returns NaN.

score 2 · Answer 6 · answered Feb 03 '18 at 09:48

2

It is fairly risky to rely on javascript functions to compare and play with numbers. In javascript (0.1+0.2 == 0.3) will return false due to rounding errors. Use the math.js library.

answered Feb 03 '18 at 09:48

dondrzzy

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sidonaldson · Answer 7 · 2023-02-09T12:01:37.527

2

I made a little helper function to do this and catch all malformed data

const convertToPounds = (str = "", asNumber = false) => {
  let num = Number.parseFloat(str);
  if (isNaN(num) || num < 0) num = 0;
  if (asNumber) return Math.round(num * 1e2) / 1e2
  return num.toFixed(2);
};

Demo is here

edited Feb 09 '23 at 12:01

answered Mar 07 '18 at 10:54

sidonaldson

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This function returns a string, not a number! – Mario Nezmah Feb 09 '23 at 11:24
@MarioNezmah good point. Have updated to allow the option to return a number. I used toFixed because I was using it to display the converted number on a webpage so it made sense – sidonaldson Feb 09 '23 at 12:02

score 0 · Answer 8 · answered Jan 23 '22 at 07:08

Prefix + could be used to convert a string form of a number to a number (say "009" to 9)

const myNum = +"009"; // 9

But be careful if you want to SUM 2 or more number strings into one number.

const myNum = "001" + "009";   // "001009"  (NOT 10)

const myNum = +"001" + +"009"; // 10

Alternatively you can do

const myNum = Number("001") + Number("009"); // 10

convert a JavaScript string variable to decimal/money

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