diff --git a/build/webpack.dev.config.js b/build/webpack.dev.config.js
index d58ac4ac..9c18a9da 100644
--- a/build/webpack.dev.config.js
+++ b/build/webpack.dev.config.js
@@ -6,7 +6,7 @@ const baseWebpackConfig = require('./webpack.base.config')
 const utils = require('./utils')
 
 const webpackConfig = merge(baseWebpackConfig, {
-  devtool: '#cheap-module-eval-source-map',
+  // devtool: '#cheap-module-eval-source-map',
   plugins: [
     new webpack.HotModuleReplacementPlugin(),
     // https://github.com/ampedandwired/html-webpack-plugin
diff --git a/src/component/vector-source/source.vue b/src/component/vector-source/source.vue
index 880116db..bc33797a 100644
--- a/src/component/vector-source/source.vue
+++ b/src/component/vector-source/source.vue
@@ -2,7 +2,7 @@
   import VectorSource from 'ol/source/Vector'
   import { vectorSource } from '../../mixin'
   import { createGeoJsonFmt, getFeatureId, initializeFeature, loadingAll, transform } from '../../ol-ext'
-  import { constant, difference, isEqual, isFinite, isFunction, stubArray } from '../../util/minilo'
+  import { constant, difference, isEqual, isFinite, isFunction, stubArray, isArray, isString } from '../../util/minilo'
   import { makeWatchers } from '../../util/vue-helpers'
 
   export default {
@@ -82,10 +82,10 @@
             resolution,
             this.resolvedDataProjection,
           )
-          if (!Array.isArray(features)) {
+          if (isString(features) && features !== '') {
             features = this.readSourceData(features)
           }
-          if (Array.isArray(features)) {
+          if (isArray(features)) {
             this.addFeatures(features)
           }
         }
diff --git a/test/app.vue b/test/app.vue
index 519badf3..fac4a3aa 100644
--- a/test/app.vue
+++ b/test/app.vue
@@ -12,7 +12,7 @@
       </vl-layer-tile>
 
       <vl-layer-vector>
-        <vl-source-vector :features.sync="features"></vl-source-vector>
+        <vl-source-vector ref="vectorSource" :features.sync="features" :loader-factory="loader"></vl-source-vector>
         <vl-style-func :factory="styleFactory" />
       </vl-layer-vector>
 
@@ -22,7 +22,7 @@
 </template>
 
 <script>
-  import { createStyle } from '../src/ol-ext'
+  import { createStyle, readGeoJsonFeature } from '../src/ol-ext'
 
   export default {
     name: 'app',
@@ -40,17 +40,17 @@
         return this.selectedFeatures.map(({ id }) => id)
       },
     },
-    mounted () {
-      this.loadFeatures().then(features => {
-        this.features = features.map(Object.freeze)
-      })
-    },
     methods: {
+      loader () {
+        return async () => {
+          await this.loadFeatures()
+        }
+      },
       loadFeatures() {
         return new Promise(resolve => {
           setTimeout(() => {
             // generate GeoJSON random features
-            resolve([{
+            const features = [{
               type: "Feature",
               geometry: {
                 type: 'Point',
@@ -136,7 +136,12 @@
                   active: false,
                 },
               },
-            ])
+            ]
+            features.forEach(feature => {
+              feature = readGeoJsonFeature(feature)
+              this.$refs.vectorSource.addFeature(feature)
+            })
+            resolve()
           }, 3000)
         })
       },