Problems in using vue

when del deletes the previous line, the next line will automatically expand if there is any content. Why, please help solve it. Thank you!

the following is all the code

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <style>
        body {
            font-family: Menlo, Consolas, monospace;
            color: -sharp444;
        }

        .item {
            cursor: pointer;
        }

        .bold {
            font-weight: bold;
        }

        ul {
            padding-left: 1em;
            line-height: 1.5em;
            list-style-type: dot;
        }
    </style>
    <script src="https://cdn.bootcss.com/vue/2.4.2/vue.min.js"></script>
</head>
<body>
<script type="text/x-template" id="item-template">
    <li>
        <div :class="{bold: isFolder}" @click="toggle" @dblclick="changeType">
            {{ model.name }}
            <span v-if="isFolder">[{{ open ? "-" : "+" }}]</span>
            <span class="bold" @click="$emit("del", index)">[del]</span>
        </div>
        <ul v-if="isFolder" v-show="open">
            <item class="item" v-for="(item, index) in model.children" :key="index" :index="index" :model="item" @del="model.children.splice($event, 1)"></item>
            <li class="add" @click="addChild">+</li>
        </ul>
    </li>
</script>

<ul id="demo"> <item class="item" v-for="(model, index) in treeData" :key="index" :index="index" :model="model" @del="treeData.splice($event, 1)"></item> </ul> <script> var data = [ {name: "han"}, {name: "wang"}, { name: "liu", children: [ {name: "zhang"}, {name: "lu"} ] } ]; Vue.component("item", { template: "-sharpitem-template", props: { model: Object, index: Number }, data: function () { return { open: false } }, computed: { isFolder: function () { return this.model.children && this.model.children.length; } }, methods: { toggle: function () { if (this.isFolder) { this.open = !this.open; } }, changeType: function () { if (!this.isFolder) { Vue.set(this.model, "children", []); this.addChild(); this.open = true; } }, addChild: function () { this.model.children.push({ name: "new child" }); } } }); var demo = new Vue({ el: "-sharpdemo", data: { treeData: data } }); </script> </body> </html>
Mar.19,2021

first of all, your item key here uses an array subscript, which causes a problem. When the second is deleted, the subscript of the original third becomes 2, which causes the click del operation to raise the toggle event and switch the open state.
there are two ways to solve this problem: 1. Add .stop to @ click= "$emit ('del', index)") to stop bubbling;

                2.  key   :key="index + model.name"
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b35b75-2bfb1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b35b75-2bfb1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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