4 files changed, 53 insertions, 14 deletions
diff --git a/runtime/js/06_util.js b/runtime/js/06_util.js
index e04ae7bd7..971957b7e 100644
--- a/runtime/js/06_util.js
+++ b/runtime/js/06_util.js
@@ -5,18 +5,27 @@ const {
   Promise,
   SafeArrayIterator,
 } = primordials;
-let logDebug = false;
+
+// WARNING: Keep this in sync with Rust (search for LogLevel)
+const LogLevel = {
+  Error: 1,
+  Warn: 2,
+  Info: 3,
+  Debug: 4,
+};
+
+let logLevel = 3;
 let logSource = "JS";
 
-function setLogDebug(debug, source) {
-  logDebug = debug;
+function setLogLevel(level, source) {
+  logLevel = level;
   if (source) {
     logSource = source;
   }
 }
 
 function log(...args) {
-  if (logDebug) {
+  if (logLevel >= LogLevel.Debug) {
     // if we destructure `console` off `globalThis` too early, we don't bind to
     // the right console, therefore we don't log anything out.
     globalThis.console.error(
@@ -80,6 +89,6 @@ export {
   log,
   nonEnumerable,
   readOnly,
-  setLogDebug,
+  setLogLevel,
   writable,
 };
diff --git a/runtime/js/99_main.js b/runtime/js/99_main.js
index 91d34272f..8fd9a6bd9 100644
--- a/runtime/js/99_main.js
+++ b/runtime/js/99_main.js
@@ -299,7 +299,7 @@ function runtimeStart(
   v8Version,
   tsVersion,
   target,
-  debugFlag,
+  logLevel,
   noColor,
   isTty,
   source,
@@ -315,7 +315,7 @@ function runtimeStart(
     tsVersion,
   );
   core.setBuildInfo(target);
-  util.setLogDebug(debugFlag, source);
+  util.setLogLevel(logLevel, source);
   setNoColor(noColor || !isTty);
   // deno-lint-ignore prefer-primordials
   Error.prepareStackTrace = core.prepareStackTrace;
@@ -428,7 +428,7 @@ function bootstrapMainRuntime(runtimeOptions) {
   const {
     0: args,
     1: cpuCount,
-    2: debugFlag,
+    2: logLevel,
     3: denoVersion,
     4: locale,
     5: location_,
@@ -495,7 +495,7 @@ function bootstrapMainRuntime(runtimeOptions) {
     v8Version,
     tsVersion,
     target,
-    debugFlag,
+    logLevel,
     noColor,
     isTty,
   );
@@ -542,7 +542,7 @@ function bootstrapWorkerRuntime(
   const {
     0: args,
     1: cpuCount,
-    2: debugFlag,
+    2: logLevel,
     3: denoVersion,
     4: locale,
     5: location_,
@@ -610,7 +610,7 @@ function bootstrapWorkerRuntime(
     v8Version,
     tsVersion,
     target,
-    debugFlag,
+    logLevel,
     noColor,
     isTty,
     internalName ?? name,
diff --git a/runtime/lib.rs b/runtime/lib.rs
index 50822d373..1e307f492 100644
--- a/runtime/lib.rs
+++ b/runtime/lib.rs
@@ -35,3 +35,4 @@ pub mod worker;
 
 mod worker_bootstrap;
 pub use worker_bootstrap::BootstrapOptions;
+pub use worker_bootstrap::WorkerLogLevel;
diff --git a/runtime/worker_bootstrap.rs b/runtime/worker_bootstrap.rs
index ba894f52b..9627281a6 100644
--- a/runtime/worker_bootstrap.rs
+++ b/runtime/worker_bootstrap.rs
@@ -6,13 +6,42 @@ use std::thread;
 
 use crate::colors;
 
+/// The log level to use when printing diagnostic log messages, warnings,
+/// or errors in the worker.
+///
+/// Note: This is disconnected with the log crate's log level and the Rust code
+/// in this crate will respect that value instead. To specify that, use
+/// `log::set_max_level`.
+#[derive(Debug, Default, Clone, Copy)]
+pub enum WorkerLogLevel {
+  // WARNING: Ensure this is kept in sync with
+  // the JS values (search for LogLevel).
+  Error = 1,
+  Warn = 2,
+  #[default]
+  Info = 3,
+  Debug = 4,
+}
+
+impl From<log::Level> for WorkerLogLevel {
+  fn from(value: log::Level) -> Self {
+    match value {
+      log::Level::Error => WorkerLogLevel::Error,
+      log::Level::Warn => WorkerLogLevel::Warn,
+      log::Level::Info => WorkerLogLevel::Info,
+      log::Level::Debug => WorkerLogLevel::Debug,
+      log::Level::Trace => WorkerLogLevel::Debug,
+    }
+  }
+}
+
 /// Common bootstrap options for MainWorker & WebWorker
 #[derive(Clone)]
 pub struct BootstrapOptions {
   /// Sets `Deno.args` in JS runtime.
   pub args: Vec<String>,
   pub cpu_count: usize,
-  pub debug_flag: bool,
+  pub log_level: WorkerLogLevel,
   pub enable_testing_features: bool,
   pub locale: String,
   pub location: Option<ModuleSpecifier>,
@@ -44,7 +73,7 @@ impl Default for BootstrapOptions {
       no_color: !colors::use_color(),
       is_tty: colors::is_tty(),
       enable_testing_features: Default::default(),
-      debug_flag: Default::default(),
+      log_level: Default::default(),
       ts_version: Default::default(),
       locale: "en".to_string(),
       location: Default::default(),
@@ -77,7 +106,7 @@ impl BootstrapOptions {
     }
 
     {
-      let val = v8::Boolean::new(scope, self.debug_flag);
+      let val = v8::Integer::new(scope, self.log_level as i32);
       array.set_index(scope, 2, val.into());
     }