added virtual scroll list for log view

frontend/src/components/ScrollView/LogItem.vue

@@ -0,0 +1,39 @@
+<template>
+  <div class="log-item">
+    <div class="line-no">{{index}}</div>
+    <div class="line-content">{{data}}</div>
+  </div>
+</template>
+
+<script>
+export default {
+  name: 'LogItem',
+  props: {
+    index: {
+      type: Number,
+      default: 1
+    },
+    data: {
+      type: String,
+      default: ''
+    }
+  }
+}
+</script>
+
+<style scoped>
+  .log-item {
+    display: flex;
+  }
+
+  .log-item .line-no {
+    margin-right: 10px;
+    text-align: right;
+    flex-basis: 40px;
+  }
+
+  .log-item .line-content {
+    display: inline-block;
+    flex-basis: calc(100% - 50px);
+  }
+</style>

frontend/src/components/ScrollView/LogView.vue

@@ -0,0 +1,78 @@
+<template>
+  <virtual-list
+    :size="18"
+    :remain="100"
+    :item="item"
+    :itemcount="logData.length"
+    :itemprops="getItemProps"
+  >
+  </virtual-list>
+</template>
+
+<script>
+import LogItem from './LogItem'
+import VirtualList from 'vue-virtual-scroll-list'
+
+export default {
+  name: 'LogView',
+  components: {
+    VirtualList
+  },
+  props: {
+    data: {
+      type: String,
+      default: ''
+    }
+  },
+  data () {
+    return {
+      item: LogItem
+    }
+  },
+  computed: {
+    logData () {
+      return this.data.split('\n')
+        .map((d, i) => {
+          return {
+            index: i + 1,
+            data: d
+          }
+        })
+    }
+  },
+  methods: {
+    getItemProps (index) {
+      const logItem = this.logData[index]
+      return {
+        // <item/> will render with itemProps.
+        // https://vuejs.org/v2/guide/render-function.html#createElement-Arguments
+        props: {
+          index: logItem.index,
+          data: logItem.data
+        }
+      }
+    }
+  },
+  mounted () {
+  }
+}
+</script>
+
+<style scoped>
+  .log-view {
+    min-height: 100%;
+    overflow-y: scroll;
+    list-style: none;
+  }
+
+  .log-view .log-line {
+    display: flex;
+  }
+
+  .log-view .log-line:nth-child(odd) {
+  }
+
+  .log-view .log-line:nth-child(even) {
+  }
+
+</style>