js: port more methods (os, builtin) (#12238)

vlib/builtin/js/builtin.js.v

@@ -83,6 +83,10 @@ fn js_stacktrace() string {
 	return stacktrace
 }
 
+pub fn print_backtrace() {
+	println(js_stacktrace())
+}
+
 // Check for nil value
 pub fn isnil(val voidptr) bool {
 	res := false

vlib/builtin/js/builtin.v

@@ -6,6 +6,7 @@ module builtin
 
 fn (a any) toString()
 
+[noreturn]
 pub fn panic(s string) {
 	eprintln('V panic: $s\n$js_stacktrace()')
 	exit(1)

vlib/builtin/js/int.js.v

@@ -155,3 +155,35 @@ pub fn (b []byte) hex() string {
 	}
 	return hex
 }
+
+pub fn (i int) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i i8) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i i16) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i i64) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i byte) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i u16) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i u32) hex2() string {
+	return '0x' + i.hex()
+}
+
+pub fn (i u64) hex2() string {
+	return '0x' + i.hex()
+}

vlib/builtin/js/string.js.v

@@ -910,3 +910,10 @@ pub fn (s string) index(search string) ?int {
 	}
 	return res
 }
+
+pub fn (_rune string) utf32_code() int {
+	res := 0
+	#res.val = s.str.charCodeAt()
+
+	return res
+}