Add Node version matrix to Azure DevOps Pipeline

azure-pipelines.yml

@@ -1,6 +1,4 @@
-# Node.js
-# Build a general Node.js project with npm.
-# Add steps that analyze code, save build artifacts, deploy, and more:
+# Azure DevOps Pipeline for Node.js
 # https://docs.microsoft.com/azure/devops/pipelines/languages/javascript
 
 trigger:
@@ -9,10 +7,19 @@ trigger:
 pool:
   vmImage: 'ubuntu-latest'
 
+strategy:
+  matrix:
+    node_8_x:
+      node_version: 8.x
+    node_10_x:
+      node_version: 10.x
+    node_12_x:
+      node_version: 12.x
+
 steps:
 - task: NodeTool@0
   inputs:
-    versionSpec: '10.x'
+    versionSpec: $(node_version)
   displayName: 'Install Node.js'
 
 - script: |