Why Not a Function #29: decimal-fmt

(import '[goog.i18n NumberFormat] '[goog.i18n.NumberFormat Format])

(defn decimal-fmt
  ([x] (decimal-fmt x 2))
  ([x digits] (decimal-fmt x digits digits))
  ([x min-digits max-digits]
   (.format
     (doto (NumberFormat. Format.DECIMAL)
       (.setMinimumFractionDigits min-digits)
       (.setMaximumFractionDigits max-digits))
     x)))

decimal-fmt is almost a reverse of parse-num from the previous blog. It is a ClojureScript wrapper around Google Closure’s NumberFormat allowing formatting of decimal numbers with rounding using a current Google Closure locale. We specify the number of decimal digits we want to include. Moreover, we can use a nice NumberFormat feature which automatically selects minimum decimal digits required from a given range to represent our value.

(decimal-fmt 1.55555)
=> "1.56"

(decimal-fmt 1.55555 0 3)
=> "1.556"

(decimal-fmt 1.0 0 3)
=> "1"

Written on April 22, 2020