fix: number locale support

Add support for Number.toLocaleString() which was previously just using
toString.

Fixes #285

builtin_number.go

@@ -3,6 +3,10 @@ package otto
 import (
 	"math"
 	"strconv"
+
+	"golang.org/x/text/language"
+	"golang.org/x/text/message"
+	"golang.org/x/text/number"
 )
 
 // Number
@@ -96,5 +100,13 @@ func builtinNumber_isNaN(call FunctionCall) Value {
 }
 
 func builtinNumber_toLocaleString(call FunctionCall) Value {
-	return builtinNumber_toString(call)
+	value := call.thisClassObject(classNumber).primitiveValue()
+	locale := call.Argument(0)
+	lang := defaultLanguage
+	if locale.IsDefined() {
+		lang = language.MustParse(locale.string())
+	}
+
+	p := message.NewPrinter(lang)
+	return toValue_string(p.Sprintf("%v", number.Decimal(value.value)))
 }

go.mod

@@ -4,6 +4,7 @@ go 1.18
 
 require (
 	github.com/stretchr/testify v1.8.1
+	golang.org/x/text v0.4.0
 	gopkg.in/readline.v1 v1.0.0-20160726135117-62c6fe619375
 	gopkg.in/sourcemap.v1 v1.0.5
 )

go.sum

@@ -14,6 +14,8 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+golang.org/x/text v0.4.0 h1:BrVqGRd7+k1DiOgtnFvAkoQEWQvBc25ouMJM6429SFg=
+golang.org/x/text v0.4.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/readline.v1 v1.0.0-20160726135117-62c6fe619375 h1:hPki/oSSWOLiI9Gc9jyIoj33O3j29fUc9PlLha2yDj0=

issue_test.go

@@ -1122,3 +1122,12 @@ func Test_issue177(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, float64(9), exp)
 }
+
+func Test_issue285(t *testing.T) {
+	vm := New()
+	val, err := vm.Run(`(1451).toLocaleString('en-US')`)
+	require.NoError(t, err)
+	exp, err := val.Export()
+	require.NoError(t, err)
+	require.Equal(t, "1,451", exp)
+}

locale.go

@@ -0,0 +1,7 @@
+package otto
+
+import "golang.org/x/text/language"
+
+var (
+	defaultLanguage = language.MustParse("en-US")
+)