fix(h5): web-view 组件重复加载(http://ask.dcloud.net.cn/question/71466)

src/platforms/h5/view/components/web-view/index.vue

-<template>
-  <uni-web-view>
-    <iframe
-      :src="$getRealPath(src)"
-      frameborder="0"
-      width="100%"
-      height="100%" />
-  </uni-web-view>
-</template>
-<script>
-export default {
-  name: 'WebView',
-  props: {
-    src: {
-      type: String,
-      default: ''
+<template>
+  <uni-web-view />
+</template>
+<script>
+export default {
+  name: 'WebView',
+  props: {
+    src: {
+      type: String,
+      default: ''
+    }
+  },
+  watch: {
+    src (val, oldVal) {
+      this.iframe && (this.iframe.src = this.$getRealPath(this.src))
     }
-  }
-}
-</script>
-<style>
-	uni-web-view iframe {
-		position: absolute;
-	}
+  },
+  mounted () {
+    const {
+      top,
+      bottom,
+      width,
+      height
+    } = this.$el.getBoundingClientRect()
+
+    this.iframe = document.createElement('iframe')
+    this.iframe.style.position = 'absolute'
+    this.iframe.style.display = 'block'
+    this.iframe.style.border = 0
+    this.iframe.style.top = top + 'px'
+    this.iframe.style.bottom = bottom + 'px'
+    this.iframe.style.width = width + 'px'
+    this.iframe.style.height = height + 'px'
+    this.iframe.src = this.$getRealPath(this.src)
+
+    document.body.appendChild(this.iframe)
+  },
+  activated () {
+    this.iframe.style.display = 'block'
+  },
+  deactivated () {
+    this.iframe.style.display = 'none'
+  },
+  beforeDestroy () {
+    document.body.removeChild(this.iframe)
+  }
+}
+</script>
+<style>
+    uni-web-view {
+        position: absolute;
+        left: 0;
+        right: 0;
+        top: 0;
+        bottom: 0;
+    }
 </style>