html / vue 自动生成目录

<template>
    <div style="padding: 20px">
        <div class="menuBox">
            <p>目录</p>
            <el-scrollbar ref="scrollMenuRef" class="scrollMenuBox">
                <aside v-for="i in menuList" :key="i" v-html="i.title"></aside>
            </el-scrollbar>
        </div>
        <div class="contentBox">
            <main v-for="i in Total" :key="i">
                <h1>一级标题{{i}}</h1>
                <p>内容{{i}}</p>
                <p>内容{{i}}</p>
                <p>内容{{i}}</p>
                <p>内容{{i}}</p>
                <h2>二级标题{{i}}</h2>
                <p>内容{{i}}</p>
                <p>内容{{i}}</p>
                <p>内容{{i}}</p>
                <p>内容{{i}}</p>
            </main>
        </div>
    </div>
</template>
<script>
    export default {
        data() {
            return {
                menuList: [],
                Total: 60
            }
        },
        mounted() {
            [...document.getElementsByTagName("main")]
                .forEach(item => {
                    [...item.children].forEach(
                        item2 => {
                            if (item2.tagName === "H1") {
                                this.menuList.push(
                                    {
                                        content: item2.innerText,
                                        title: item2.outerHTML,
                                        level: 1,
                                        offsetTop: item2.offsetTop
                                    }
                                )
                            }
                            if (item2.tagName === "H2") {
                                this.menuList.push(
                                    {
                                        content: item2.innerText,
                                        title: item2.outerHTML,
                                        level: 2,
                                        offsetTop: item2.offsetTop
                                    }
                                )
                            }
                            if (item2.tagName === "H3") {
                                this.menuList.push(
                                    {
                                        content: item2.innerText,
                                        title: item2.outerHTML,
                                        level: 3,
                                        offsetTop: item2.offsetTop
                                    }
                                )
                            }
                            if (item2.tagName === "H4") {
                                this.menuList.push(
                                    {
                                        content: item2.innerText,
                                        title: item2.outerHTML,
                                        level: 4,
                                        offsetTop: item2.offsetTop
                                    }
                                )
                            }
                            if (item2.tagName === "H5") {
                                this.menuList.push(
                                    {
                                        content: item2.innerText,
                                        title: item2.outerHTML,
                                        level: 5,
                                        offsetTop: item2.offsetTop
                                    }
                                )
                            }
                            if (item2.tagName === "H6") {
                                this.menuList.push(
                                    {
                                        content: item2.innerText,
                                        title: item2.outerHTML,
                                        level: 6,
                                        offsetTop: item2.offsetTop
                                    }
                                )
                            }
                        }
                    )
                })
        },
    }
</script>
<style scoped>
    /*目录悬浮*/
    .menuBox {
        position: fixed;
    }
 
    /*内容居中*/
    .contentBox {
        width: 60%;
        margin: auto;
    }
 
    /*el-scrollbar 必须指定高度*/
    .scrollMenuBox {
        height: 600px;
        width: 200px;
    }
 
    /*隐藏水平滚动条*/
    /deep/ .el-scrollbar__wrap {
        overflow-x: hidden;
    }
</style>