官方文档 https://www.npmjs.com/package/diff

安装：npm install diff

内容

 <template>
    <div>
      <div style="white-space: pre-line;display: flex;">
        <div>
            <span class="default">{{oldStr}}</span>
        </div>
        <div>
         <span v-for="(item,index) in resultStr" :key="index" :class="item.added?'add':item.removed?'remove':'default'">{{item.value}}</span>
        </div>
      </div>
    </div>
  </template>
<script>
import {diffChars} from 'diff'
export default {
  name: 'CodeMirror',
  data() {
    return {
      resultStr: '',
      chineseStr: `让顾明渊和阮念心这对渣男贱女血债血偿！`,
      oldStr: `should try our best to help others when they are in need of help，but we should also protect ourselves from getting into trouble．If everyone tries a little kindness，our world will be full of love．`,
      newStr: `our best to help others when they are in need of help，but we also should also protect ourselves from getting into trouble．If everyone tries a little kindness，our world will be full of love．`
    };
  },
  mounted() {
    const d = diffChars(this.oldStr, this.newStr)
    this.resultStr = d
  }
};
</script>
<style scoped>
  .remove {
    color: red;
    background-color: #fee8e9;
    text-decoration: line-through;
  }
  .add {
    color: green;
    background-color: #ddffdd;
  }
  .default {
    color: grey;
  }
</style>

实例结果：