删除重复 vue.js

Question

I have a button that when pressed adds words and saves them in local storage. When pressed more than once, it adds the same words. I want to delete repeated words What is the problem and what is the solution?

code in this link: https://www.w3schools.com/code/tryit.asp?filename=GTS8415TXXGZ

Answer 1

<template>
  <div id="app">
    <section class="todo-wrapper">
      <form @keydown.enter.prevent="">
        <div v-bind:class="{ active: new_todo }" @click="addItem">+</div>
      </form>

      <div v-if="pending.length > 0">
        <transition-group name="todo-item" tag="ul" class="todo-list">
          <li v-for="(item, index) in pending" v-bind:key="index">
            <span class="delete" @click="deleteItem(index)">
              <span class="todo-text">{{ item.title }}</span></span
            >
          </li>
        </transition-group>
      </div>

      <transition name="slide-fade">
        <p class="status free" v-if="!pending.length">
          <img src="empty.svg" alt="empty" />empty
        </p>
      </transition>
    </section>
  </div>
</template>
<script>
export default {
  el: "#app",
  data() {
    return {
      todoList: [],
      new_todo: "",
      showComplete: false,
      showCanNotAdd: false,
    };
  },

  computed: {},
  mounted() {
    localStorage.setItem("count", "one");
    this.getTodos();
  },
  watch: {
    todoList: {
      handler: function (updatedList) {
        localStorage.setItem("todo_list", JSON.stringify(updatedList));
      },
      deep: true,
    },
  },
  computed: {
    pending: function () {
      return this.todoList.filter(function (item) {
        return !item.done;
      });
    },
    completed: function () {
      return this.todoList.filter(function (item) {
        return item.done;
      });
    },
    completedPercentage: function () {
      return (
        Math.floor((this.completed.length / this.todoList.length) * 100) + "%"
      );
    },
    today: function () {
      var weekday = [
        "Sunday",
        "Monday",
        "Tuesday",
        "Wednesday",
        "Thursday",
        "Friday",
        "Saturday",
      ];
      var today = new Date();
      var dd = today.getDate();
      var mm = today.getMonth() + 1; //January is 0!
      var yyyy = today.getFullYear();

      if (dd < 10) {
        dd = "0" + dd;
      }

      if (mm < 10) {
        mm = "0" + mm;
      }

      today = {
        day: weekday[today.getDay()],
        date: mm + "-" + dd + "-" + yyyy,
      };
      return today;
    },
  },
  methods: {
    getTodos() {
      if (localStorage.getItem("todo_list")) {
        this.todoList = JSON.parse(localStorage.getItem("todo_list"));
      }
    },
    addItem() {
      if (condition) {
        
      }
      this.todoList.unshift({
        id: this.todoList.length,
        title: "click " + localStorage.getItem("count"),
        done: false,
      });
      this.new_todo = "";
      return true;
    },
    deleteItem(index) {
      this.todoList.splice(index, 1);
    },
  },
};
</script>

try this out