docs: add example for build --mode env (vuejs#902)

ksherman · yyx990803 · commit 9b1d37680091 · 2018-02-28T18:33:59.000-05:00
* docs: add docs on using --mode with build command to use corresponding env vars

* Use the arg.mode in the console log "Building for..." message
diff --git a/docs/env.md b/docs/env.md
@@ -37,6 +37,12 @@ Note that a mode is different from `NODE_ENV`, as a mode can contain multiple en
 
 You can set environment variables only available to a certain mode by postfixing the `.env` file. For example, if you create a file named `.env.development` in your project root, then the variables declared in that file will only be loaded in development mode.
 
+Passing the `--mode` option flag with [build command](https://github.com/vuejs/vue-cli/blob/dev/docs/cli-service.md#build) will use that mode's environment variables in the build. For example, if you want to use development variables in the build command, add this to your package.json scripts:
+
+```
+"dev-build": "vue-cli-service build --mode development",
+```
+
 ### Using Env Variables in Client-side Code
 
 Only variables that start with `VUE_APP_` will be statically embedded into the client bundle with `webpack.DefinePlugin`. You can access them in your application code:
diff --git a/packages/@vue/cli-service/lib/commands/build/index.js b/packages/@vue/cli-service/lib/commands/build/index.js
@@ -46,11 +46,11 @@ module.exports = (api, options) => {
 
     log()
     if (args.target === 'app') {
-      logWithSpinner(`Building for production...`)
+      logWithSpinner(`Building for ${args.mode}...`)
     } else {
       const buildMode = buildModes[args.target]
       if (buildMode) {
-        logWithSpinner(`Building for production as ${buildMode}...`)
+        logWithSpinner(`Building for ${args.mode} as ${buildMode}...`)
       } else {
         throw new Error(`Unknown build target: ${args.target}`)
       }
