[javascript] How to convert string into float in JavaScript?

I am trying to parse two values from a datagrid. The fields are numeric, and when they have a comma (ex. 554,20), I can't get the numbers after the comma. I've tried parseInt and parseFloat. How can I do this?

If someone is looking for a way to parse float from an arbitrary string,

it can be done like that:

function extractFloat(text) {
  const match = text.match(/\d+((\.|,)\d+)?/)
  return match && match[0]
}

extractFloat('some text with float 5.25') // 5.25

I had the same problem except I did not know in advance what were the thousands separators and the decimal separator. I ended up writing a library to do this. If you are interested it here it is : https://github.com/GuillaumeLeclerc/number-parsing

If you extend String object like this..

String.prototype.float = function() { 
  return parseFloat(this.replace(',', '.')); 
}

.. you can run it like this

"554,20".float()
> 554.20

works with dot as well

"554.20".float()
> 554.20

typeof "554,20".float()
> "number"

@GusDeCool or anyone else trying to replace more than one thousands separators, one way to do it is a regex global replace: /foo/g. Just remember that . is a metacharacter, so you have to escape it or put it in brackets (\. or [.]). Here's one option:

var str = '6.000.000';
str.replace(/[.]/g,",");

Have you ever tried to do this? :p

var str = '3.8';ie
alert( +(str) + 0.2 );

+(string) will cast string into float.

Handy!

So in order to solve your problem, you can do something like this:

var floatValue = +(str.replace(/,/,'.'));

You can use this function. It will replace the commas with ' ' and then it will parseFlaot the value and after that it will again adjust the commas in value.

function convertToFloat(val) {
        if (val != '') {
            if (val.indexOf(',') !== -1)
                val.replace(',', '');
            val = parseFloat(val);
            while (/(\d+)(\d{3})/.test(val.toString())) {
                val = val.toString().replace(/(\d+)(\d{3})/, '$1' + ',' + '$2');
            }
        }
        return val;
    }

Try

let str ="554,20";_x000D_
let float = +str.replace(',','.');_x000D_
let int = str.split(',').map(x=>+x);_x000D_
_x000D_
console.log({float,int});

Replace the comma with a dot.

This will only return 554:

var value = parseFloat("554,20")

This will return 554.20:

var value = parseFloat("554.20")

So in the end, you can simply use:

var fValue = parseFloat(document.getElementById("textfield").value.replace(",","."))

Don't forget that parseInt() should only be used to parse integers (no floating points). In your case it will only return 554. Additionally, calling parseInt() on a float will not round the number: it will take its floor (closest lower integer).

Extended example to answer Pedro Ferreira's question from the comments:

If the textfield contains thousands separator dots like in 1.234.567,99 those could be eliminated beforehand with another replace:

var fValue = parseFloat(document.getElementById("textfield").value.replace(/\./g,"").replace(",","."))