Vue implements book management case

<style type="text/css">
    .grid {
      margin: auto;
      width: 550px;
      text-align: center;
    }

    .grid table {
      width: 100%;
      border-collapse: collapse;
    }

    .grid th,
    td {
      padding: 10;
      border: 1px dashed orange;
      height: 35px;
    }

    .grid th {
      background-color: orange;
    }

    .grid .book {
      width: 550px;
      padding-bottom: 10px;
      padding-top: 5px;
      background-color: lawngreen;
    }

    .grid .total {
      height: 30px;
      line-height: 30px;
      background-color: lawngreen;
      border-top: 1px solid orange;
    }
</style>

<div id="app">
    <div class='grid'>
      <div>
        <h1>Book Management</h1>
        <div class="book">
          <div>
            <label for='id'>
              serial number:
            </label>
            <input type="text" id="id" v-model='id' :disabled='flag' v-focus>
            <label for="name">
              name:
            </label>
            <input type="text" id='name' v-model='name'>
            <button @click='handle' :disabled='submitFlag'>Submit</button>
          </div>
        </div>
      </div>
      <div class='total'>
        <span>Total number of books:</span><span>{{total}}</span>
      </div>
      <table>
        <thead>
          <tr>
            <th>Number</th>
            <th>Name</th>
            <th>Time</th>
            <th>Operation</th>
          </tr>
        </thead>
        <tbody>
          <tr :key="item.id" v-for="item in books">
            <td>{{item.id}}</td>
            <td>{{item.name}}</td>
            <td>{{item.date | format('yyyy-MM-dd hh:MM:ss')}}</td>
            <td><a href="" @click.prevent='toEdit(item.id)'>Edit</a>
              <span>|</span>
              <a href="" @click.prevent='deleteBook(item.id)'>Delete</a>
            </td>
          </tr>

        </tbody>
      </table>
    </div>
</div>

<script type="text/javascript" src="../js/vue.js"></script>
  <script type="text/javascript">
    Vue.directive('focus', {
      inserted: function (el) {
        el.focus();
      }
    })
    Vue.filter('format', function (value, arg) {
      function dateFormat(date, format) {
        if (typeof date === "string") {
          var mts = date.match(/(\/Date\((\d +)\)\/)/);
          if (mts && mts.length >= 3) {
            date = parseInt(mts[2]);
          }
        }
        date = new Date(date);
        if (!date || date.toUTCString() == "Invalid Date") {
          return "";
        }
        var map = {
          "M": date.getMonth() + 1, //month "d": date.getDate(), //day "h": date.getHours(), //hours "m": date.getMinutes(), //minutes "s": date.getSeconds(), //seconds "q": Math.floor((date.getMonth() + 3) / 3), //quarter "S": date.getMilliseconds() //milliseconds };
        format = format.replace(/([yMdhmsqS])+/g, function (all, t) {
          var v = map[t];
          if (v != undefined) {
            if (all.length > 1) {
              v = '0' + v;
              v = v.substr(v.length - 2);
            }
            return v;
          } else if (t === 'y') {
            return (date.getFullYear() + '').substr(4 - all.length);
          }
          return all;
        });
        return format;
      }
      return dateFormat(value, arg);
    })
    var vm = new Vue({
      el: '#app',
      data: {
        flag: false,
        submitFlag: false,
        id: '',
        name: '',
        books: []
      },
      methods: {
        handle: function () {
          if (this.flag) {
            // Edit operation // is to update the corresponding data in the array according to the current id this.books.some((item) => {
              if (item.id == this.id) {
                item.name = this.name
                //Terminate the loop after completing the update operation return true;
              }
            })
            this.flag = false;
          } else {
            // Add a book var book = {};
            book.id = this.id;
            book.name = this.name;
            this.data = '';
            this.books.push(book);
          }
          // Clear the form this.id = '';
          this.name = '';
        }, toEdit: function (id) {
          // Disable modification of id
          this.flag = true;
          // Query the data to be edited based on id var book = this.books.filter(function (item) {
            return item.id == id;
          });
          console.log(book)
          //Submit the obtained id to the form this.id = book[0].id;
          this.name = book[0].name;
        },
        deleteBook: function (id) {
          // Delete books // Find the index of the element from the array according to the id // var index = this.books.findIndex(function (item) {
          // return item.id == id;
          // });
          // Delete array elements according to index // this.books.splice(index, 1)
          // -----------------
          // Method 2: Delete by filter method this.books = this.books.filter(function (item) {
            return item.id != id;
          })
        }
      },
      computed: {
        total: function () {
          // Calculate the total number of books return this.books.length;
        }
      },
      watch:
        name: function (val) {
          // Verify that the book name already exists var flag = this.books.some(function (item) { return item.name == val; })
          if (flag) {
            // Book name exists this.submitFlag = true
          } else {
            // The book name does not exist this.submitFlag = false
          }
        }

      },
      mounted: function () {
        // When the lifecycle hook function is triggered. The template is ready to use // Generally used to obtain background data and then fill the data into the template var data = [{
          id: 1,
          name: 'Romance of the Three Kingdoms',
          date: 252597867777

        }, {
          id: 2,
          name: 'Water Margin',
          date: 564634563453
        }, {
          id: 3,
          name: 'Dream of Red Mansions',
          date: 345435345343
        }, {
          id: 4,
          name: 'Journey to the West',
          date: 345345346533
        }]
        this.books = data
      }
    });
</script>