Update readme, add parallel testing

.github/workflows/javascript.yml

@@ -66,6 +66,11 @@ jobs:
     - name: Install dependencies
       run: make jsdependencies
 
-    - name: Run tests
+    - name: Run tests (serially)
+      if: ${{ matrix.version == 22 && matrix.os == 'ubuntu-latest' }}
       run: make jstest
 
+    - name: Run tests (in parallel)
+      if: ${{ !(matrix.version == 22 && matrix.os == 'ubuntu-latest') }}
+      run: make jstest_auto
+

javascript/Makefile

@@ -4,9 +4,11 @@ HAS_NPM?=$(shell command -v npm > /dev/null 2>&1 ; echo $$?)
 test: dependencies
 	npx mocha
 
+test_auto: dependencies
+	npx mocha --parallel
+
 test_%: dependencies
-	echo "WARNING: multithreaded tests not supported on javascript"
-	npx mocha
+	npx mocha -parallel -j $*
 
 ifneq ($(HAS_NPM),0)
 ifeq ($(OS),Windows_NT)  # if no NPM and Windows

javascript/README.rst

@@ -18,7 +18,7 @@ utilities for other problems to use.
 Makefile
 --------
 
-There are two main recipes in this Makefile
+There are four main recipes in this Makefile
 
 dependencies
 ~~~~~~~~~~~~
@@ -34,6 +34,20 @@ each. This test infrastructure is based on mocha and benchmark.js,
 though it currently does not export benchmark info except to fail tests
 for time limit reasons.
 
+test\_\*
+~~~~~~~~
+
+This recipe runs tests in the specified number of threads and performs
+benchmarks on each. This test infrastructure is based on mocha and benchmark.js,
+though it currently does not export benchmark info except to fail tests
+for time limit reasons. If you specify the number of threads as `auto`, it
+will default to using 1 fewer threads than you have CPUs.
+
+lint
+~~~~
+
+This recipe runs es-lint on the JavaScript files.
+
 Tests
 -----