JS: decode unicode escape sequences in strings to UTF-8 literals

go.mod

@@ -10,6 +10,6 @@ require (
 	github.com/matryer/try v0.0.0-20161228173917-9ac251b645a2
 	github.com/spf13/pflag v1.0.5
 	github.com/tdewolff/parse/v2 v2.6.6
-	github.com/tdewolff/test v1.0.7
+	github.com/tdewolff/test v1.0.9
 	golang.org/x/sys v0.6.0 // indirect
 )

go.sum

@@ -12,8 +12,9 @@ github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/tdewolff/parse/v2 v2.6.6 h1:Yld+0CrKUJaCV78DL1G2nk3C9lKrxyRTux5aaK/AkDo=
 github.com/tdewolff/parse/v2 v2.6.6/go.mod h1:woz0cgbLwFdtbjJu8PIKxhW05KplTFQkOdX78o+Jgrs=
-github.com/tdewolff/test v1.0.7 h1:8Vs0142DmPFW/bQeHRP3MV19m1gvndjUb1sn8yy74LM=
 github.com/tdewolff/test v1.0.7/go.mod h1:6DAvZliBAAnD7rhVgwaM7DE5/d9NMOAJ09SqYqeK4QE=
+github.com/tdewolff/test v1.0.9 h1:SswqJCmeN4B+9gEAi/5uqT0qpi1y2/2O47V/1hhGZT0=
+github.com/tdewolff/test v1.0.9/go.mod h1:6DAvZliBAAnD7rhVgwaM7DE5/d9NMOAJ09SqYqeK4QE=
 golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0 h1:MVltZSvRTcU2ljQOhs94SXPftV6DCNnZViHeQps87pQ=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

js/js_test.go

@@ -149,11 +149,13 @@ func TestJS(t *testing.T) {
 		{`"string\t\f\v\bstring"`, "\"string\t\f\v\bstring\""},
 		{`"string\a\c\'string"`, `"stringac'string"`},
 		{`"string\∀string"`, `"string∀string"`},
-		{`"string\0\uFFFFstring"`, "\"string\x00\\uFFFFstring\""},
+		{`"string\0\uFFFFstring"`, "\"string\x00string\""},
 		{`"string\x00\x55\x0A\x0D\x22\x27string"`, "\"string\x00U\\n\\r\\\"'string\""},
 		{`"string\000\12\015\042\47\411string"`, "\"string\x00\\n\\r\\\"'!1string\""},
 		{"'string\\n\\rstring'", "`string\n\rstring`"},
 		{"'string\\\r\nstring\\\nstring\\\rstring\\\u2028string\\\u2029string'", `"stringstringstringstringstringstring"`},
+		{`"\x7H\u877H"`, `"\x7H\u877H"`},
+		{`"\u01ac\u01de\u0187\u{0001a0}"`, `"ƬǞƇƠ"`},
 		{`"str1ng" + "str2ng"`, `"str1ngstr2ng"`},
 		{`"str1ng" + "str2ng" + "str3ng"`, `"str1ngstr2ngstr3ng"`},
 		{`"padding" + this`, `"padding"+this`},
@@ -793,8 +795,8 @@ func TestJS(t *testing.T) {
 		{`var a=5;({});var b=class{c(){3}}`, `var b,a=5;({},b=class{c(){3}})`},                                                                             // #494
 		{`({});a={b(){3}}`, `({},a={b(){3}})`},                                                                                                             // #494
 		{`export default function Foo(){a}Foo.prototype.bar=b`, `export default function Foo(){a}Foo.prototype.bar=b`},                                     // #525
-		{`(e=1,e=2)`, `e=1,e=2`},            // #528
-		{`"\x00\x31 \0"`, "\"\x001 \x00\""}, // #577
+		{`(e=1,e=2)`, `e=1,e=2`},                      // #528
+		{`"\x00\x31 \0\u0000"`, "\"\x001 \x00\x00\""}, // #577
 	}
 
 	m := minify.New()

js/util.go

@@ -3,6 +3,8 @@ package js
 import (
 	"bytes"
 	"encoding/hex"
+	stdStrconv "strconv"
+	"unicode/utf8"
 
 	"github.com/tdewolff/minify/v2"
 	"github.com/tdewolff/parse/v2/js"
@@ -981,7 +983,7 @@ func replaceEscapes(b []byte, quote byte, prefix, suffix int) []byte {
 	for i := prefix; i < len(b)-suffix; i++ {
 		if c := b[i]; c == '\\' {
 			c = b[i+1]
-			if c == quote || c == '\\' || c == 'u' || quote != '`' && (c == 'n' || c == 'r') {
+			if c == quote || c == '\\' || quote != '`' && (c == 'n' || c == 'r') {
 				// keep escape sequence
 				i++
 				continue
@@ -1014,6 +1016,36 @@ func replaceEscapes(b []byte, quote byte, prefix, suffix int) []byte {
 					i++
 					continue
 				}
+			} else if c == 'u' && i+2 < len(b) {
+				l := i + 2
+				if b[i+2] == '{' {
+					l++
+				}
+				r := l
+				for ; r < len(b) && (b[i+2] == '{' || r < l+4); r++ {
+					if b[r] < '0' || '9' < b[r] && b[r] < 'A' || 'F' < b[r] && b[r] < 'a' || 'f' < b[r] {
+						break
+					}
+				}
+				if b[i+2] == '{' && 6 < r-l || b[i+2] != '{' && r-l != 4 {
+					i++
+					continue
+				}
+				num, err := stdStrconv.ParseInt(string(b[l:r]), 16, 32)
+				if err != nil || 0x10FFFF <= num {
+					i++
+					continue
+				}
+
+				// decode unicode character to UTF-8 and put at the end of the escape sequence
+				// then skip the first part of the escape sequence until the decoded character
+				n = 2 + r - l
+				if b[i+2] == '{' {
+					n += 2
+				}
+				m := utf8.RuneLen(rune(num))
+				utf8.EncodeRune(b[i+n-m:], rune(num))
+				n -= m
 			} else if c == '0' && (i+2 == len(b)-1 || b[i+2] < '0' || '7' < b[i+2]) {
 				// \0 (NULL)
 				b[i+1] = '\x00'