diff --git a/vlib/builtin/js/builtin.js.v b/vlib/builtin/js/builtin.js.v
index 99f451814c..a676acc19c 100644
--- a/vlib/builtin/js/builtin.js.v
+++ b/vlib/builtin/js/builtin.js.v
@@ -2,8 +2,11 @@ module builtin
 
 // used to generate JS throw statements.
 
+[noreturn]
 pub fn js_throw(s any) {
 	#throw s
+
+	for {}
 }
 
 #let globalPrint;
@@ -46,6 +49,7 @@ pub fn eprint(s string) {
 // Exits the process in node, and halts execution in the browser
 // because `process.exit` is undefined. Workaround for not having
 // a 'real' way to exit in the browser.
+[noreturn]
 pub fn exit(c int) {
 	JS.process.exit(c)
 	js_throw('exit($c)')
diff --git a/vlib/builtin/js/byte.js.v b/vlib/builtin/js/byte.js.v
index c2bee28d0f..0a75772f10 100644
--- a/vlib/builtin/js/byte.js.v
+++ b/vlib/builtin/js/byte.js.v
@@ -68,3 +68,29 @@ pub fn (c byte) is_letter() bool {
 pub fn (c byte) is_alnum() bool {
 	return c.is_letter() || c.is_digit()
 }
+
+// Define this on byte as well, so that we can do `s[0].is_capital()`
+pub fn (c byte) is_capital() bool {
+	return c >= `A` && c <= `Z`
+}
+
+// str_escaped returns the contents of `byte` as an escaped `string`.
+// Example: assert byte(0).str_escaped() == r'`\0`'
+
+pub fn (b byte) str_escaped() string {
+	mut str := ''
+	match b {
+		0 { str = r'`\0`' }
+		7 { str = r'`\a`' }
+		8 { str = r'`\b`' }
+		9 { str = r'`\t`' }
+		10 { str = r'`\n`' }
+		11 { str = r'`\v`' }
+		12 { str = r'`\f`' }
+		13 { str = r'`\r`' }
+		27 { str = r'`\e`' }
+		32...126 { str = b.ascii_str() }
+		else { str = '0x' + b.hex() }
+	}
+	return str
+}
diff --git a/vlib/builtin/js/string.js.v b/vlib/builtin/js/string.js.v
index d07bb5982e..126a4ca236 100644
--- a/vlib/builtin/js/string.js.v
+++ b/vlib/builtin/js/string.js.v
@@ -900,3 +900,13 @@ pub fn (s []string) join(sep string) string {
 
 // There's no better way to find length of JS String in bytes.
 #Object.defineProperty(string.prototype,"len", { get: function() {return new int(new TextEncoder().encode(this.str).length);}, set: function(l) {/* ignore */ } });
+// index returns the position of the first character of the input string.
+// It will return `none` if the input string can't be found.
+pub fn (s string) index(search string) ?int {
+	res := 0
+	#res.val = s.str.indexOf(search)
+	if res == -1 {
+		return none
+	}
+	return res
+}
diff --git a/vlib/os/os.js.v b/vlib/os/os.js.v
index c1641db3dd..87cf0e91f1 100644
--- a/vlib/os/os.js.v
+++ b/vlib/os/os.js.v
@@ -37,19 +37,36 @@ pub fn flush() {
 	}
 }
 
+pub fn getpid() int {
+	res := 0
+	#res.val = $process.pid
+
+	return res
+}
+
 // chmod change file access attributes of `path` to `mode`.
 // Octals like `0o600` can be used.
-pub fn chmod(path string, mode int) {
+pub fn chmod(path string, mode int) ? {
 	$if js_node {
+		#try {
 		#$fs.chmodSync(''+path,mode.valueOf())
+		#} catch (error) {
+		#return error_with_code(new string("chmod failed: " + error.message),new int(error.code))
+		#}
+	} $else {
+		return error('os.chmod() is available only for NodeJS')
 	}
 }
 
 // chown changes the owner and group attributes of `path` to `owner` and `group`.
 // Octals like `0o600` can be used.
-pub fn chown(path string, owner int, group int) {
+pub fn chown(path string, owner int, group int) ? {
 	$if js_node {
+		#try {
 		#$fs.chownSync(''+path,owner.valueOf(),group.valueOf())
+		#} catch (error) { return error_with_code(new string("chown failed: " + error.message),new int(error.code)) }
+	} $else {
+		return error('os.chown() is available only for NodeJS')
 	}
 }
 
@@ -89,7 +106,7 @@ pub fn execute(cmd string) Result {
 	#let commands = cmd.str.split(' ');
 	#let output = $child_process.spawnSync(commands[0],commands.slice(1,commands.length));
 	#exit_code = new int(output.status)
-	#stdout = newstring(output.stdout + '')
+	#stdout = new string(output.stdout + '')
 
 	return Result{
 		exit_code: exit_code
@@ -97,6 +114,14 @@ pub fn execute(cmd string) Result {
 	}
 }
 
+pub fn system(cmd string) int {
+	exit_code := 0
+	#let commands = cmd.str.split(' ');
+	#exit_code.val = $child_process.execSync(commands[0],commands.slice(1,commands.length));
+
+	return exit_code
+}
+
 pub fn is_atty(fd int) int {
 	res := 0
 	#res.val = +tty.isatty(fd.val)
diff --git a/vlib/rand/rand.js.v b/vlib/rand/rand.js.v
index ce4ea265c2..4171801be0 100644
--- a/vlib/rand/rand.js.v
+++ b/vlib/rand/rand.js.v
@@ -1,5 +1,7 @@
 module rand
 
+import time
+
 // init initializes the default RNG.
 fn init() {
 	default_rng = new_default()
@@ -15,3 +17,51 @@ pub fn string(len int) string {
 
 	return result
 }
+
+const (
+	ulid_encoding = '0123456789ABCDEFGHJKMNPQRSTVWXYZ'
+)
+
+// ulid generates an Unique Lexicographically sortable IDentifier.
+// See https://github.com/ulid/spec .
+// NB: ULIDs can leak timing information, if you make them public, because
+// you can infer the rate at which some resource is being created, like
+// users or business transactions.
+// (https://news.ycombinator.com/item?id=14526173)
+pub fn ulid() string {
+	return ulid_at_millisecond(u64(time.utc().unix_time_milli()))
+}
+
+// ulid_at_millisecond does the same as `ulid` but takes a custom Unix millisecond timestamp via `unix_time_milli`.
+pub fn ulid_at_millisecond(unix_time_milli u64) string {
+	mut buf := []byte{cap: 27}
+	mut t := unix_time_milli
+	mut i := 9
+	for i >= 0 {
+		buf[i] = rand.ulid_encoding[int(t & 0x1f)]
+		t = t >> 5
+		i--
+	}
+
+	mut x := default_rng.u64()
+	i = 10
+	for i < 19 {
+		buf[i] = rand.ulid_encoding[int(x & 0x1f)]
+
+		x = x >> 5
+		i++
+	}
+
+	x = default_rng.u64()
+	for i < 26 {
+		buf[i] = rand.ulid_encoding[int(x & 0x1f)]
+		x = x >> 5
+		i++
+	}
+
+	res := ''
+	println(buf)
+	#res.str = buf.arr.arr.map(String.fromCharCode).join('')
+
+	return res
+}
diff --git a/vlib/v/pref/os.v b/vlib/v/pref/os.v
index 578b00d00e..e546e54b30 100644
--- a/vlib/v/pref/os.v
+++ b/vlib/v/pref/os.v
@@ -112,5 +112,18 @@ pub fn get_host_os() OS {
 	$if haiku {
 		return .haiku
 	}
+	$if js_node {
+		return .js_node
+	}
+	$if js_freestanding {
+		return .js_freestanding
+	}
+
+	$if js_browser {
+		return .js_browser
+	}
+	$if js {
+		return .js_node
+	}
 	panic('unknown host OS')
 }
diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index 48980fdb25..fd918ab196 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -171,6 +171,9 @@ pub fn launch_tool(is_verbose bool, tool_name string, args []string) {
 	}
 	$if windows {
 		exit(os.system('"$tool_exe" $tool_args'))
+	} $else $if js {
+		// no way to implement os.execvp in JS backend
+		exit(os.system('$tool_exe $tool_args'))
 	} $else {
 		os.execvp(tool_exe, args) or { panic(err) }
 	}