How do I calculate my item quantity by checking dates within 30 days of the current date?

Here are the current codes I need to add to my items within 30 days

<template>
  <div>
    <div>
      <div class="tree">
         <table width="100%"  border="1">
              <tr>
                <th>row</th>
                <th>Item</th>
                <th>Category</th>
                <th>Date</th>
                <th>Description</th>
              </tr>
              <tr v-for="(user,index) in bookData" v-bind:key="user.listData">
                <td>{{ user.index }}</td>
                <td>{{ user.item_id }}</td>
                <td>{{ user.category_id }}</td>
                <td>{{ user.r_date }}</td>
                <td>{{ user.description }}</td>
              </tr>
            </table>
            **New Item within 30 days :** 
        <div>
      </div>
    </div>
  </div>
</div>
</template>

<script lang="ts">
import { Vue, Watch, Component } from 'vue-property-decorator';
import API from '@/API';

@Component
export default class BookTable extends Vue {
  private bookData: any = [];
  private tempData: any = [];
  private metadata: any = JSON.stringify([], undefined, 2) ;

  private created(): void {
    this.getBookDetails();
    if (this.currentUser) {
      this.getCategories();
    }
  }

  @Watch('categories')
  private getBookDetails(): void {
    if (this.categories.length > 0) {
      for (const category of this.categories) {
        API.Book.getBook(category.id).then((response) => {
          this.bookData = this.bookData.concat(response ? response : []);
          this.tempData = this.bookData;
        });
      }
    }
  }
}
</script>

Please help as I'm trying to learn more about Vue and am very new to it and typescript.