feats

src/components/barcode/index.jsx

       <Canvas style={style} type='2d' id={id}></Canvas>
       {
         codeVisible && <CodeText code={code} />
-      }      
+      }
+      {
+        !code && <View className='no-barcode'>暂无条码</View>
+      }
     </View>
   )
 }

src/components/barcode/style.less

 .barcode-box {
+  position: relative;
+
   .barcode-txt {
     display: flex;
     justify-content: space-between;
       flex: 1;
     }
   }
+
+  .no-barcode {
+    position: absolute;
+    width: 100%;
+    height: 100%;
+    font-size: 2em;
+    color: rgba(0, 0, 0, .5);
+    line-height: 3em;
+    z-index: 100;
+    top: 0;
+    left: 0;
+    text-align: center;
+  }
 }