Apply a simple mask to a String. You can customize the mask template and which Char to replace.

string { mask = "+1 ### ### ####", replace = '#' } "1234567890"
--> "+1 123 456 7890"

Remove a mask applied by string. This is often needed if you want to save just the value, and not the formatted/masked String.

remove { mask = "+1 ### ### ####", replace = '#' } "+1 123 456 7890"
--> "1234567890"


remove { mask = "+1 ### ### ####", replace = '#' } "1234567890"
-->"1234567890"

When formatting with float and floatString, it can be useful to either use exactly an amount of decimal digits, or just to limit it to a certain amount.

Mask a float to have a certain amount of DecimalDigits.

float (Precisely 2) 123
--> "123.00"


float (Precisely 2) 123.4
--> "123.40"


float (Precisely 2) 123.4567
--> "123.45"


float (AtMost 2) 123
--> "123"


float (AtMost 2) 123.4
--> "123.4"


float (AtMost 2) 123.4567
--> "123.45"

Mask a float to have a certain amount of DecimalDigits, but using a String as an input. This is useful for input fields, where the onInput event returns a String that can be run through floatString. In case the input String is not a valid Float, this function returns Nothing, and an empty String is automatically converted to 0.

floatString (Precisely 2) "123.4"
--> Just "123.40"


floatString (Precisely 2) "12a.4"
--> Nothing


floatString (Precisely 2) ""
--> Just "0.00"

Usually you'll want to use this function in your update like this:

update msg model =
    case msg of
        EnteredPrice price ->
            { model
                | price =
                    price
                        |> Mask.floatString (Mask.Precisely 2)
                        |> Maybe.withDefault model.price
            }