[Build] revert site to webpack config (#3747)

build/webpack.build.js

@@ -0,0 +1,33 @@
+const path = require('path');
+const config = require('./webpack.dev.js');
+
+const isMinify = process.argv.indexOf('-p') !== -1;
+
+delete config.serve;
+
+module.exports = Object.assign(config, {
+  mode: 'production',
+  entry: {
+    vant: './es/index.js'
+  },
+  output: {
+    path: path.join(__dirname, '../lib'),
+    library: 'vant',
+    libraryTarget: 'umd',
+    filename: isMinify ? '[name].min.js' : '[name].js',
+    umdNamedDefine: true,
+    globalObject: 'this'
+  },
+  externals: {
+    vue: {
+      root: 'Vue',
+      commonjs: 'vue',
+      commonjs2: 'vue',
+      amd: 'vue'
+    }
+  },
+  performance: false,
+  optimization: {
+    minimize: isMinify
+  }
+});