From 5b5b3892d3dee6c321c836147a4403be7e706ca8 Mon Sep 17 00:00:00 2001
From: Steve Sanderson <SteveSandersonMS@users.noreply.github.com>
Date: Fri, 8 Dec 2017 10:27:46 +0000
Subject: [PATCH] Auto-restore NPM dependencies on build

---
 .../Microsoft.Blazor.Browser.csproj                 | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/Microsoft.Blazor.Browser/Microsoft.Blazor.Browser.csproj b/src/Microsoft.Blazor.Browser/Microsoft.Blazor.Browser.csproj
index 6be0ffdc5c..320d3d14af 100644
--- a/src/Microsoft.Blazor.Browser/Microsoft.Blazor.Browser.csproj
+++ b/src/Microsoft.Blazor.Browser/Microsoft.Blazor.Browser.csproj
@@ -15,9 +15,18 @@
     <WebpackInputs Include="**\*.ts" Exclude="node_modules\**" />
   </ItemGroup>
 
-  <Target Name="RunWebpack" BeforeTargets="PreBuildEvent" Inputs="@(WebpackInputs)" Outputs="dist\blazor.js">
+  <Target Name="EnsureNpmRestored" Condition="!Exists('node_modules')">
+    <Exec Command="node --version" ContinueOnError="true">
+      <Output TaskParameter="ExitCode" PropertyName="ErrorCode" />
+    </Exec>
+    <Error Condition="'$(ErrorCode)' != '0'" Text="Node.js is required to build and run this project. To continue, please install Node.js from https://nodejs.org/, and then restart your command prompt or IDE." />
+    <Message Importance="high" Text="Restoring dependencies using 'npm'. This may take several minutes..." />
+    <Exec Command="npm install" />
+  </Target>
+
+  <Target Name="RunWebpack" BeforeTargets="PreBuildEvent" Inputs="@(WebpackInputs)" Outputs="dist\blazor.js" DependsOnTargets="EnsureNpmRestored">
     <RemoveDir Directories="dist" />
-    <Exec Command="npm run build" WorkingDirectory="$(MSBuildThisFileDirectory)" />
+    <Exec Command="npm run build" />
     <ItemGroup>
       <EmbeddedResource Include="dist\blazor.js" LogicalName="blazor.$blazor.js" />
     </ItemGroup>