diff --git a/app/assets/javascripts/discourse-js-processor.js b/app/assets/javascripts/discourse-js-processor.js
index 7050fe2ac77..0e038ec87fa 100644
--- a/app/assets/javascripts/discourse-js-processor.js
+++ b/app/assets/javascripts/discourse-js-processor.js
@@ -1,4 +1,4 @@
-/* global Babel:true */
+/* global Babel:true Terser:true */
 
 // This is executed in mini_racer to provide the JS logic for lib/discourse_js_processor.rb
 
@@ -110,3 +110,29 @@ exports.transpile = function (
     throw error;
   }
 };
+
+// mini_racer doesn't have native support for getting the result of an async operation.
+// To work around that, we provide a getMinifyResult which can be used to fetch the result
+// in a followup method call.
+let lastMinifyError, lastMinifyResult;
+
+exports.minify = async function (sources, options) {
+  lastMinifyError = lastMinifyResult = null;
+  try {
+    lastMinifyResult = await Terser.minify(sources, options);
+  } catch (e) {
+    lastMinifyError = e;
+  }
+};
+
+exports.getMinifyResult = function () {
+  const error = lastMinifyError;
+  const result = lastMinifyResult;
+
+  lastMinifyError = lastMinifyResult = null;
+
+  if (error) {
+    throw error;
+  }
+  return result;
+};
diff --git a/app/controllers/theme_javascripts_controller.rb b/app/controllers/theme_javascripts_controller.rb
index 77ad53f05cb..418a076b825 100644
--- a/app/controllers/theme_javascripts_controller.rb
+++ b/app/controllers/theme_javascripts_controller.rb
@@ -9,10 +9,10 @@ class ThemeJavascriptsController < ApplicationController
     :preload_json,
     :redirect_to_login_if_required,
     :verify_authenticity_token,
-    only: [:show, :show_tests]
+    only: [:show, :show_map, :show_tests]
   )
 
-  before_action :is_asset_path, :no_cookies, :apply_cdn_headers, only: [:show, :show_tests]
+  before_action :is_asset_path, :no_cookies, :apply_cdn_headers, only: [:show, :show_map, :show_tests]
 
   def show
     raise Discourse::NotFound unless last_modified.present?
@@ -21,18 +21,29 @@ class ThemeJavascriptsController < ApplicationController
     # Security: safe due to route constraint
     cache_file = "#{DISK_CACHE_PATH}/#{params[:digest]}.js"
 
-    unless File.exist?(cache_file)
-      content = query.pluck_first(:content)
-      raise Discourse::NotFound if content.nil?
-
-      FileUtils.mkdir_p(DISK_CACHE_PATH)
-      File.write(cache_file, content)
+    write_if_not_cached(cache_file) do
+      content, has_source_map = query.pluck_first(:content, "source_map IS NOT NULL")
+      if has_source_map
+        content += "\n//# sourceMappingURL=#{params[:digest]}.map?__ws=#{Discourse.current_hostname}\n"
+      end
+      content
     end
 
-    # this is only required for NGINX X-SendFile it seems
-    response.headers["Content-Length"] = File.size(cache_file).to_s
-    set_cache_control_headers
-    send_file(cache_file, disposition: :inline)
+    serve_file(cache_file)
+  end
+
+  def show_map
+    raise Discourse::NotFound unless last_modified.present?
+    return render body: nil, status: 304 if not_modified?
+
+    # Security: safe due to route constraint
+    cache_file = "#{DISK_CACHE_PATH}/#{params[:digest]}.map"
+
+    write_if_not_cached(cache_file) do
+      query.pluck_first(:source_map)
+    end
+
+    serve_file(cache_file)
   end
 
   def show_tests
@@ -48,14 +59,11 @@ class ThemeJavascriptsController < ApplicationController
     @cache_file = "#{TESTS_DISK_CACHE_PATH}/#{digest}.js"
     return render body: nil, status: 304 if not_modified?
 
-    if !File.exist?(@cache_file)
-      FileUtils.mkdir_p(TESTS_DISK_CACHE_PATH)
-      File.write(@cache_file, content)
+    write_if_not_cached(@cache_file) do
+      content
     end
 
-    response.headers["Content-Length"] = File.size(@cache_file).to_s
-    set_cache_control_headers
-    send_file(@cache_file, disposition: :inline)
+    serve_file @cache_file
   end
 
   private
@@ -94,4 +102,22 @@ class ThemeJavascriptsController < ApplicationController
       immutable_for(1.year)
     end
   end
+
+  def write_if_not_cached(cache_file)
+    unless File.exist?(cache_file)
+      content = yield
+      raise Discourse::NotFound if content.nil?
+
+      FileUtils.mkdir_p(File.dirname(cache_file))
+      File.write(cache_file, content)
+    end
+  end
+
+  def serve_file(cache_file)
+    # this is only required for NGINX X-SendFile it seems
+    response.headers["Content-Length"] = File.size(cache_file).to_s
+    set_cache_control_headers
+    type = cache_file.end_with?(".map") ? "application/json" : "text/javascript"
+    send_file(cache_file, type: type, disposition: :inline)
+  end
 end
diff --git a/app/models/javascript_cache.rb b/app/models/javascript_cache.rb
index 85a31c94c4e..794a4ef612d 100644
--- a/app/models/javascript_cache.rb
+++ b/app/models/javascript_cache.rb
@@ -41,6 +41,7 @@ end
 #  created_at     :datetime         not null
 #  updated_at     :datetime         not null
 #  theme_id       :bigint
+#  source_map     :text
 #
 # Indexes
 #
diff --git a/app/models/theme.rb b/app/models/theme.rb
index 1f9f23e548e..662dc1c890e 100644
--- a/app/models/theme.rb
+++ b/app/models/theme.rb
@@ -6,7 +6,7 @@ require 'json_schemer'
 class Theme < ActiveRecord::Base
   include GlobalPath
 
-  BASE_COMPILER_VERSION = 64
+  BASE_COMPILER_VERSION = 65
 
   attr_accessor :child_components
 
@@ -127,7 +127,7 @@ class Theme < ActiveRecord::Base
       settings_hash = build_settings_hash
       js_compiler.prepend_settings(settings_hash) if settings_hash.present?
       javascript_cache || build_javascript_cache
-      javascript_cache.update!(content: js_compiler.content)
+      javascript_cache.update!(content: js_compiler.content, source_map: js_compiler.source_map)
     else
       javascript_cache&.destroy!
     end
@@ -717,13 +717,17 @@ class Theme < ActiveRecord::Base
 
     compiler = ThemeJavascriptCompiler.new(id, name)
     compiler.append_tree(tests_tree, for_tests: true)
-    content = compiler.content
-
-    content = <<~JS + content
+    compiler.append_raw_script "test_setup.js", <<~JS
       (function() {
         require("discourse/lib/theme-settings-store").registerSettings(#{self.id}, #{cached_default_settings.to_json}, { force: true });
       })();
     JS
+    content = compiler.content
+
+    if compiler.source_map
+      content += "\n//# sourceMappingURL=data:application/json;base64,#{Base64.strict_encode64(compiler.source_map)}\n"
+    end
+
     [content, Digest::SHA1.hexdigest(content)]
   end
 
diff --git a/app/models/theme_field.rb b/app/models/theme_field.rb
index 90d9aa9db89..475e3541565 100644
--- a/app/models/theme_field.rb
+++ b/app/models/theme_field.rb
@@ -95,6 +95,7 @@ class ThemeField < ActiveRecord::Base
           js_compiler.append_ember_template("discourse/templates/#{name}", hbs_template)
         end
       rescue ThemeJavascriptCompiler::CompileError => ex
+        js_compiler.append_js_error("discourse/templates/#{name}", ex.message)
         errors << ex.message
       end
 
@@ -128,25 +129,23 @@ class ThemeField < ActiveRecord::Base
 
         js_compiler.append_module(js, "discourse/initializers/#{initializer_name}", include_variables: true)
       rescue ThemeJavascriptCompiler::CompileError => ex
+        js_compiler.append_js_error("discourse/initializers/#{initializer_name}", ex.message)
         errors << ex.message
       end
 
       node.remove
     end
 
-    doc.css('script').each do |node|
+    doc.css('script').each_with_index do |node, index|
       next unless inline_javascript?(node)
-      js_compiler.append_raw_script(node.inner_html)
+      js_compiler.append_raw_script("_html/#{Theme.targets[self.target_id]}/#{name}_#{index + 1}.js", node.inner_html)
       node.remove
     end
 
-    errors.each do |error|
-      js_compiler.append_js_error(error)
-    end
-
     settings_hash = theme.build_settings_hash
-    js_compiler.prepend_settings(settings_hash) if js_compiler.content.present? && settings_hash.present?
+    js_compiler.prepend_settings(settings_hash) if js_compiler.has_content? && settings_hash.present?
     javascript_cache.content = js_compiler.content
+    javascript_cache.source_map = js_compiler.source_map
     javascript_cache.save!
 
     doc.add_child("<script defer src='#{javascript_cache.url}' data-theme-id='#{theme_id}'></script>") if javascript_cache.content.present?
@@ -239,6 +238,7 @@ class ThemeField < ActiveRecord::Base
     end
 
     javascript_cache.content = js_compiler.content
+    javascript_cache.source_map = js_compiler.source_map
     javascript_cache.save!
     doc = ""
     doc = "<script defer src='#{javascript_cache.url}' data-theme-id='#{theme_id}'></script>" if javascript_cache.content.present?
diff --git a/config/routes.rb b/config/routes.rb
index 0b1931aaeb9..ade3bfa2f38 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -561,6 +561,7 @@ Discourse::Application.routes.draw do
     get "stylesheets/:name.css" => "stylesheets#show", constraints: { name: /[-a-z0-9_]+/ }
     get "color-scheme-stylesheet/:id(/:theme_id)" => "stylesheets#color_scheme", constraints: { format: :json }
     get "theme-javascripts/:digest.js" => "theme_javascripts#show", constraints: { digest: /\h{40}/ }
+    get "theme-javascripts/:digest.map" => "theme_javascripts#show_map", constraints: { digest: /\h{40}/ }
     get "theme-javascripts/tests/:theme_id-:digest.js" => "theme_javascripts#show_tests"
 
     post "uploads/lookup-metadata" => "uploads#metadata"
diff --git a/db/migrate/20221018100550_add_source_map_to_javascript_cache.rb b/db/migrate/20221018100550_add_source_map_to_javascript_cache.rb
new file mode 100644
index 00000000000..1651e418bd3
--- /dev/null
+++ b/db/migrate/20221018100550_add_source_map_to_javascript_cache.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddSourceMapToJavascriptCache < ActiveRecord::Migration[7.0]
+  def change
+    add_column :javascript_caches, :source_map, :text
+  end
+end
diff --git a/lib/discourse_js_processor.rb b/lib/discourse_js_processor.rb
index 9f1d9c756bb..11f1ee27672 100644
--- a/lib/discourse_js_processor.rb
+++ b/lib/discourse_js_processor.rb
@@ -152,6 +152,10 @@ class DiscourseJsProcessor
         }
       JS
 
+      # Terser
+      load_file_in_context(ctx, "node_modules/source-map/dist/source-map.js")
+      load_file_in_context(ctx, "node_modules/terser/dist/bundle.min.js")
+
       # Template Compiler
       load_file_in_context(ctx, "node_modules/ember-source/dist/ember-template-compiler.js")
       load_file_in_context(ctx, "node_modules/babel-plugin-ember-template-compilation/src/plugin.js", wrap_in_module: "babel-plugin-ember-template-compilation/index")
@@ -197,6 +201,8 @@ class DiscourseJsProcessor
       ctx.eval <<~JS
         globalThis.compileRawTemplate = require('discourse-js-processor').compileRawTemplate;
         globalThis.transpile = require('discourse-js-processor').transpile;
+        globalThis.minify = require('discourse-js-processor').minify;
+        globalThis.getMinifyResult = require('discourse-js-processor').getMinifyResult;
       JS
 
       ctx
@@ -219,9 +225,16 @@ class DiscourseJsProcessor
       @ctx
     end
 
+    # Call a method in the global scope of the v8 context.
+    # The `fetch_result_call` kwarg provides a workaround for the lack of mini_racer async
+    # result support. The first call can perform some async operation, and then `fetch_result_call`
+    # will be called to fetch the result.
     def self.v8_call(*args, **kwargs)
+      fetch_result_call = kwargs.delete(:fetch_result_call)
       mutex.synchronize do
-        v8.call(*args, **kwargs)
+        result = v8.call(*args, **kwargs)
+        result = v8.call(fetch_result_call) if fetch_result_call
+        result
       end
     rescue MiniRacer::RuntimeError => e
       message = e.message
@@ -276,5 +289,8 @@ class DiscourseJsProcessor
       self.class.v8_call("compileRawTemplate", source, theme_id)
     end
 
+    def terser(tree, opts)
+      self.class.v8_call("minify", tree, opts, fetch_result_call: "getMinifyResult")
+    end
   end
 end
diff --git a/lib/theme_javascript_compiler.rb b/lib/theme_javascript_compiler.rb
index 998963ef55d..b278d322c98 100644
--- a/lib/theme_javascript_compiler.rb
+++ b/lib/theme_javascript_compiler.rb
@@ -7,16 +7,78 @@ class ThemeJavascriptCompiler
   class CompileError < StandardError
   end
 
-  attr_accessor :content
+  @@terser_disabled = false
+  def self.disable_terser!
+    raise "Tests only" if !Rails.env.test?
+    @@terser_disabled = true
+  end
+
+  def self.enable_terser!
+    raise "Tests only" if !Rails.env.test?
+    @@terser_disabled = false
+  end
 
   def initialize(theme_id, theme_name)
     @theme_id = theme_id
-    @content = +""
+    @output_tree = []
     @theme_name = theme_name
   end
 
+  def compile!
+    if !@compiled
+      @compiled = true
+      @output_tree.freeze
+      output = if !has_content?
+        { "code" => "" }
+      elsif @@terser_disabled
+        { "code" => raw_content }
+      else
+        DiscourseJsProcessor::Transpiler.new.terser(@output_tree.to_h, terser_config)
+      end
+      @content = output["code"]
+      @source_map = output["map"]
+    end
+    [@content, @source_map]
+  rescue DiscourseJsProcessor::TranspileError => e
+    message = "[THEME #{@theme_id} '#{@theme_name}'] Compile error: #{e.message}"
+    @content = "console.error(#{message.to_json});\n"
+    [@content, @source_map]
+  end
+
+  def terser_config
+    # Based on https://github.com/ember-cli/ember-cli-terser/blob/28df3d90a5/index.js#L12-L26
+    {
+      sourceMap: { includeSources: true, root: "theme-#{@theme_id}/" },
+      compress: {
+        negate_iife: false,
+        sequences: 30,
+      },
+      output: {
+        semicolons: false,
+      },
+    }
+  end
+
+  def content
+    compile!
+    @content
+  end
+
+  def source_map
+    compile!
+    @source_map
+  end
+
+  def raw_content
+    @output_tree.map { |filename, source| source }.join("")
+  end
+
+  def has_content?
+    @output_tree.present?
+  end
+
   def prepend_settings(settings_hash)
-    @content.prepend <<~JS
+    @output_tree.prepend ['settings.js', <<~JS]
       (function() {
         if ('require' in window) {
           require("discourse/lib/theme-settings-store").registerSettings(#{@theme_id}, #{settings_hash.to_json});
@@ -90,16 +152,17 @@ class ThemeJavascriptCompiler
       elsif extension == "hbr"
         append_raw_template(module_name.sub("discourse/templates/", ""), content)
       else
-        append_js_error("unknown file extension '#{extension}' (#{filename})")
+        append_js_error(filename, "unknown file extension '#{extension}' (#{filename})")
       end
     rescue CompileError => e
-      append_js_error "#{e.message} (#{filename})"
+      append_js_error filename, "#{e.message} (#{filename})"
     end
   end
 
   def append_ember_template(name, hbs_template)
-    name = "/#{name}" if !name.start_with?("/")
-    module_name = "discourse/theme-#{@theme_id}#{name}"
+    module_name = name
+    module_name = "/#{module_name}" if !module_name.start_with?("/")
+    module_name = "discourse/theme-#{@theme_id}#{module_name}"
 
     # Some themes are colocating connector JS under `/connectors`. Move template to /templates to avoid module name clash
     if (match = COLOCATED_CONNECTOR_REGEX.match(module_name)) && !match[:prefix].end_with?("/templates")
@@ -114,7 +177,7 @@ class ThemeJavascriptCompiler
     JS
 
     template_module = DiscourseJsProcessor.transpile(script, "", module_name, theme_id: @theme_id)
-    content << <<~JS
+    @output_tree << ["#{name}.js", <<~JS]
       if ('define' in window) {
       #{template_module}
       }
@@ -130,8 +193,12 @@ class ThemeJavascriptCompiler
 
   def append_raw_template(name, hbs_template)
     compiled = DiscourseJsProcessor::Transpiler.new.compile_raw_template(hbs_template, theme_id: @theme_id)
-    @content << <<~JS
+    source_for_comment = hbs_template.gsub("*/", '*\/').indent(4, ' ')
+    @output_tree << ["#{name}.js", <<~JS]
       (function() {
+        /*
+      #{source_for_comment}
+        */
         const addRawTemplate = requirejs('discourse-common/lib/raw-templates').addRawTemplate;
         const template = requirejs('discourse-common/lib/raw-handlebars').template(#{compiled});
         addRawTemplate(#{raw_template_name(name)}, template);
@@ -141,11 +208,12 @@ class ThemeJavascriptCompiler
     raise CompileError.new ex.message
   end
 
-  def append_raw_script(script)
-    @content << script + "\n"
+  def append_raw_script(filename, script)
+    @output_tree << [filename, script + "\n"]
   end
 
   def append_module(script, name, include_variables: true)
+    original_filename = name
     name = "discourse/theme-#{@theme_id}/#{name.gsub(/^discourse\//, '')}"
 
     # Some themes are colocating connector JS under `/templates/connectors`. Move out of templates to avoid module name clash
@@ -155,7 +223,7 @@ class ThemeJavascriptCompiler
 
     script = "#{theme_settings}#{script}" if include_variables
     transpiler = DiscourseJsProcessor::Transpiler.new
-    @content << <<~JS
+    @output_tree << ["#{original_filename}.js", <<~JS]
       if ('define' in window) {
       #{transpiler.perform(script, "", name).strip}
       }
@@ -164,9 +232,9 @@ class ThemeJavascriptCompiler
     raise CompileError.new ex.message
   end
 
-  def append_js_error(message)
+  def append_js_error(filename, message)
     message = "[THEME #{@theme_id} '#{@theme_name}'] Compile error: #{message}"
-    append_raw_script "console.error(#{message.to_json});"
+    append_raw_script filename, "console.error(#{message.to_json});"
   end
 
   private
diff --git a/spec/lib/discourse_js_processor_spec.rb b/spec/lib/discourse_js_processor_spec.rb
index 1fb2b64321f..1d87b5a85bd 100644
--- a/spec/lib/discourse_js_processor_spec.rb
+++ b/spec/lib/discourse_js_processor_spec.rb
@@ -185,4 +185,30 @@ RSpec.describe DiscourseJsProcessor do
       )
     end
   end
+
+  describe "Transpiler#terser" do
+    it "can minify code and provide sourcemaps" do
+      sources = {
+        "multiply.js" => "let multiply = (firstValue, secondValue) => firstValue * secondValue;",
+        "add.js" => "let add = (firstValue, secondValue) => firstValue + secondValue;"
+      }
+
+      result = DiscourseJsProcessor::Transpiler.new.terser(sources, { sourceMap: { includeSources: true } })
+      expect(result.keys).to contain_exactly("code", "map")
+
+      begin
+        # Check the code still works
+        ctx = MiniRacer::Context.new
+        ctx.eval(result["code"])
+        expect(ctx.eval("multiply(2, 3)")).to eq(6)
+        expect(ctx.eval("add(2, 3)")).to eq(5)
+      ensure
+        ctx.dispose
+      end
+
+      map = JSON.parse(result["map"])
+      expect(map["sources"]).to contain_exactly(*sources.keys)
+      expect(map["sourcesContent"]).to contain_exactly(*sources.values)
+    end
+  end
 end
diff --git a/spec/lib/theme_javascript_compiler_spec.rb b/spec/lib/theme_javascript_compiler_spec.rb
index 46fa810ee55..e530d3ef85e 100644
--- a/spec/lib/theme_javascript_compiler_spec.rb
+++ b/spec/lib/theme_javascript_compiler_spec.rb
@@ -8,28 +8,28 @@ RSpec.describe ThemeJavascriptCompiler do
       template = "<h1>hello</h1>"
       name = "/path/to/templates1"
       compiler.append_raw_template("#{name}.raw", template)
-      expect(compiler.content.to_s).to include("addRawTemplate(\"#{name}\"")
+      expect(compiler.raw_content.to_s).to include("addRawTemplate(\"#{name}\"")
 
       name = "/path/to/templates2"
       compiler.append_raw_template("#{name}.hbr", template)
-      expect(compiler.content.to_s).to include("addRawTemplate(\"#{name}\"")
+      expect(compiler.raw_content.to_s).to include("addRawTemplate(\"#{name}\"")
 
       name = "/path/to/templates3"
       compiler.append_raw_template("#{name}.hbs", template)
-      expect(compiler.content.to_s).to include("addRawTemplate(\"#{name}.hbs\"")
+      expect(compiler.raw_content.to_s).to include("addRawTemplate(\"#{name}.hbs\"")
     end
   end
 
   describe "#append_ember_template" do
     it 'maintains module names so that discourse-boot.js can correct them' do
       compiler.append_ember_template("/connectors/blah-1", "{{var}}")
-      expect(compiler.content.to_s).to include("define(\"discourse/theme-1/connectors/blah-1\", [\"exports\", \"@ember/template-factory\"]")
+      expect(compiler.raw_content.to_s).to include("define(\"discourse/theme-1/connectors/blah-1\", [\"exports\", \"@ember/template-factory\"]")
 
       compiler.append_ember_template("connectors/blah-2", "{{var}}")
-      expect(compiler.content.to_s).to include("define(\"discourse/theme-1/connectors/blah-2\", [\"exports\", \"@ember/template-factory\"]")
+      expect(compiler.raw_content.to_s).to include("define(\"discourse/theme-1/connectors/blah-2\", [\"exports\", \"@ember/template-factory\"]")
 
       compiler.append_ember_template("javascripts/connectors/blah-3", "{{var}}")
-      expect(compiler.content.to_s).to include("define(\"discourse/theme-1/javascripts/connectors/blah-3\", [\"exports\", \"@ember/template-factory\"]")
+      expect(compiler.raw_content.to_s).to include("define(\"discourse/theme-1/javascripts/connectors/blah-3\", [\"exports\", \"@ember/template-factory\"]")
     end
   end
 
@@ -39,22 +39,22 @@ RSpec.describe ThemeJavascriptCompiler do
       compiler = ThemeJavascriptCompiler.new(1, 'marks')
       compiler.append_ember_template("connectors/outlet/blah-1", "{{var}}")
       compiler.append_module("console.log('test')", "connectors/outlet/blah-1")
-      expect(compiler.content.to_s).to include("discourse/theme-1/connectors/outlet/blah-1")
-      expect(compiler.content.to_s).to include("discourse/theme-1/templates/connectors/outlet/blah-1")
+      expect(compiler.raw_content.to_s).to include("discourse/theme-1/connectors/outlet/blah-1")
+      expect(compiler.raw_content.to_s).to include("discourse/theme-1/templates/connectors/outlet/blah-1")
 
       # Colocated under `/templates/connectors`
       compiler = ThemeJavascriptCompiler.new(1, 'marks')
       compiler.append_ember_template("templates/connectors/outlet/blah-1", "{{var}}")
       compiler.append_module("console.log('test')", "templates/connectors/outlet/blah-1")
-      expect(compiler.content.to_s).to include("discourse/theme-1/connectors/outlet/blah-1")
-      expect(compiler.content.to_s).to include("discourse/theme-1/templates/connectors/outlet/blah-1")
+      expect(compiler.raw_content.to_s).to include("discourse/theme-1/connectors/outlet/blah-1")
+      expect(compiler.raw_content.to_s).to include("discourse/theme-1/templates/connectors/outlet/blah-1")
 
       # Not colocated
       compiler = ThemeJavascriptCompiler.new(1, 'marks')
       compiler.append_ember_template("templates/connectors/outlet/blah-1", "{{var}}")
       compiler.append_module("console.log('test')", "connectors/outlet/blah-1")
-      expect(compiler.content.to_s).to include("discourse/theme-1/connectors/outlet/blah-1")
-      expect(compiler.content.to_s).to include("discourse/theme-1/templates/connectors/outlet/blah-1")
+      expect(compiler.raw_content.to_s).to include("discourse/theme-1/connectors/outlet/blah-1")
+      expect(compiler.raw_content.to_s).to include("discourse/theme-1/templates/connectors/outlet/blah-1")
     end
   end
 
@@ -83,8 +83,8 @@ RSpec.describe ThemeJavascriptCompiler do
           "discourse/templates/components/mycomponent.hbs" => "{{my-component-template}}"
         }
       )
-      expect(compiler.content).to include('define("discourse/theme-1/components/mycomponent"')
-      expect(compiler.content).to include('define("discourse/theme-1/discourse/templates/components/mycomponent"')
+      expect(compiler.raw_content).to include('define("discourse/theme-1/components/mycomponent"')
+      expect(compiler.raw_content).to include('define("discourse/theme-1/discourse/templates/components/mycomponent"')
     end
 
     it "handles colocated components" do
@@ -97,8 +97,8 @@ RSpec.describe ThemeJavascriptCompiler do
           "discourse/components/mycomponent.hbs" => "{{my-component-template}}"
         }
       )
-      expect(compiler.content).to include("__COLOCATED_TEMPLATE__ =")
-      expect(compiler.content).to include("setComponentTemplate")
+      expect(compiler.raw_content).to include("__COLOCATED_TEMPLATE__ =")
+      expect(compiler.raw_content).to include("setComponentTemplate")
     end
 
     it "prints error when default export missing" do
@@ -111,8 +111,8 @@ RSpec.describe ThemeJavascriptCompiler do
           "discourse/components/mycomponent.hbs" => "{{my-component-template}}"
         }
       )
-      expect(compiler.content).to include("__COLOCATED_TEMPLATE__ =")
-      expect(compiler.content).to include("throw new Error")
+      expect(compiler.raw_content).to include("__COLOCATED_TEMPLATE__ =")
+      expect(compiler.raw_content).to include("throw new Error")
     end
 
     it "handles template-only components" do
@@ -121,9 +121,35 @@ RSpec.describe ThemeJavascriptCompiler do
           "discourse/components/mycomponent.hbs" => "{{my-component-template}}"
         }
       )
-      expect(compiler.content).to include("__COLOCATED_TEMPLATE__ =")
-      expect(compiler.content).to include("setComponentTemplate")
-      expect(compiler.content).to include("@ember/component/template-only")
+      expect(compiler.raw_content).to include("__COLOCATED_TEMPLATE__ =")
+      expect(compiler.raw_content).to include("setComponentTemplate")
+      expect(compiler.raw_content).to include("@ember/component/template-only")
+    end
+  end
+
+  describe "terser compilation" do
+    it "applies terser and provides sourcemaps" do
+      sources = {
+        "multiply.js" => "let multiply = (firstValue, secondValue) => firstValue * secondValue;",
+        "add.js" => "let add = (firstValue, secondValue) => firstValue + secondValue;"
+      }
+
+      compiler.append_tree(sources)
+
+      expect(compiler.content).to include("multiply")
+      expect(compiler.content).to include("add")
+
+      map = JSON.parse(compiler.source_map)
+      expect(map["sources"]).to contain_exactly(*sources.keys)
+      expect(map["sourcesContent"].to_s).to include("let multiply")
+      expect(map["sourcesContent"].to_s).to include("let add")
+      expect(map["sourceRoot"]).to eq("theme-1/")
+    end
+
+    it "handles invalid JS" do
+      compiler.append_raw_script("filename.js", "if(someCondition")
+      expect(compiler.content).to include('console.error("[THEME 1')
+      expect(compiler.content).to include('Unexpected token')
     end
   end
 end
diff --git a/spec/models/theme_field_spec.rb b/spec/models/theme_field_spec.rb
index 931bc45bf72..5a14bca2fa6 100644
--- a/spec/models/theme_field_spec.rb
+++ b/spec/models/theme_field_spec.rb
@@ -3,6 +3,8 @@
 
 RSpec.describe ThemeField do
   fab!(:theme) { Fabricate(:theme) }
+  before { ThemeJavascriptCompiler.disable_terser! }
+  after { ThemeJavascriptCompiler.enable_terser! }
 
   describe "scope: find_by_theme_ids" do
     it "returns result in the specified order" do
@@ -194,6 +196,26 @@ HTML
     expect(theme.javascript_cache.content).to include("define(\"discourse/theme-#{theme.id}/controllers/discovery-2\"")
     expect(theme.javascript_cache.content).to include("const settings =")
     expect(theme.javascript_cache.content).to include("[THEME #{theme.id} '#{theme.name}'] Compile error: unknown file extension 'blah' (discourse/controllers/discovery.blah)")
+
+    # Check sourcemap
+    expect(theme.javascript_cache.source_map).to eq(nil)
+    ThemeJavascriptCompiler.enable_terser!
+    js_field.update(compiler_version: "0")
+    theme.save!
+
+    expect(theme.javascript_cache.source_map).not_to eq(nil)
+    map = JSON.parse(theme.javascript_cache.source_map)
+
+    expect(map["sources"]).to contain_exactly(
+      "discourse/controllers/discovery-2.js",
+      "discourse/controllers/discovery.blah",
+      "discourse/controllers/discovery.js",
+      "discourse/templates/discovery.js",
+      "discovery.js",
+      "other_discovery.js"
+    )
+    expect(map["sourceRoot"]).to eq("theme-#{theme.id}/")
+    expect(map["sourcesContent"].length).to eq(6)
   end
 
   def create_upload_theme_field!(name)
diff --git a/spec/models/theme_spec.rb b/spec/models/theme_spec.rb
index cf2bc2514fb..8d513ee005a 100644
--- a/spec/models/theme_spec.rb
+++ b/spec/models/theme_spec.rb
@@ -5,6 +5,9 @@ RSpec.describe Theme do
     Theme.clear_cache!
   end
 
+  before { ThemeJavascriptCompiler.disable_terser! }
+  after { ThemeJavascriptCompiler.enable_terser! }
+
   fab! :user do
     Fabricate(:user)
   end
diff --git a/spec/requests/theme_javascripts_controller_spec.rb b/spec/requests/theme_javascripts_controller_spec.rb
index aaa24753a43..0f2c58ce584 100644
--- a/spec/requests/theme_javascripts_controller_spec.rb
+++ b/spec/requests/theme_javascripts_controller_spec.rb
@@ -2,6 +2,9 @@
 RSpec.describe ThemeJavascriptsController do
   include ActiveSupport::Testing::TimeHelpers
 
+  before { ThemeJavascriptCompiler.disable_terser! }
+  after { ThemeJavascriptCompiler.enable_terser! }
+
   def clear_disk_cache
     if Dir.exist?(ThemeJavascriptsController::DISK_CACHE_PATH)
       `rm -rf #{ThemeJavascriptsController::DISK_CACHE_PATH}`
@@ -55,6 +58,40 @@ RSpec.describe ThemeJavascriptsController do
       get "/theme-javascripts/#{javascript_cache.digest}.js"
       expect(response.status).to eq(404)
     end
+
+    it "adds sourceMappingUrl if there is a source map" do
+      digest = SecureRandom.hex(20)
+      javascript_cache.update(digest: digest)
+      get "/theme-javascripts/#{digest}.js"
+      expect(response.status).to eq(200)
+      expect(response.body).to eq('console.log("hello");')
+
+      digest = SecureRandom.hex(20)
+      javascript_cache.update(digest: digest, source_map: '{fakeSourceMap: true}')
+      get "/theme-javascripts/#{digest}.js"
+      expect(response.status).to eq(200)
+      expect(response.body).to eq <<~JS
+        console.log("hello");
+        //# sourceMappingURL=#{digest}.map?__ws=test.localhost
+      JS
+    end
+  end
+
+  describe "#show_map" do
+    it "returns a source map when present" do
+      get "/theme-javascripts/#{javascript_cache.digest}.map"
+      expect(response.status).to eq(404)
+
+      digest = SecureRandom.hex(20)
+      javascript_cache.update(digest: digest, source_map: '{fakeSourceMap: true}')
+      get "/theme-javascripts/#{digest}.map"
+      expect(response.status).to eq(200)
+      expect(response.body).to eq("{fakeSourceMap: true}")
+
+      javascript_cache.destroy
+      get "/theme-javascripts/#{digest}.map"
+      expect(response.status).to eq(404)
+    end
   end
 
   describe "#show_tests" do
@@ -133,5 +170,13 @@ RSpec.describe ThemeJavascriptsController do
       expect(response.status).to eq(200)
       expect(response.body).to include("assert.ok(343434);")
     end
+
+    it "includes inline sourcemap" do
+      ThemeJavascriptCompiler.enable_terser!
+      content, digest = component.baked_js_tests_with_digest
+      get "/theme-javascripts/tests/#{component.id}-#{digest}.js"
+      expect(response.status).to eq(200)
+      expect(response.body).to include("//# sourceMappingURL=data:application/json;base64,")
+    end
   end
 end