如何在html上获取所有元素的名称（我的错误代码运行循环）

I want to get a document tree. Then, first, I displayed all elements name. But my code run loop. How can I do?

package main

import (
    "github.com/PuerkitoBio/goquery"
    "golang.org/x/net/html"
)

func getTagName(s *goquery.Selection) {
    for _, n := range s.Nodes {
        if n.Type != html.ElementNode {
            continue
        }
        println(n.Data)
        getTagName(s.Children())
    }
}

func main() {
    doc, _ := goquery.NewDocument("https://news.ycombinator.com/")
    doc.Find("html body").Each(func(_ int, s *goquery.Selection) {
        getTagName(s)
    })
}

It seems to work with this:

package main

import (
    "os"

    "github.com/PuerkitoBio/goquery"
    "golang.org/x/net/html"
)

var areWeLooping = make(map[*goquery.Selection]struct{})

func getTagName(s *goquery.Selection) {
    if _, weAreLooping := areWeLooping[s]; weAreLooping {
        println("loop detected")
        os.Exit(1)
    }

    areWeLooping[s] = struct{}{}

    for _, n := range s.Nodes {
        if n.Type != html.ElementNode {
            continue
        }
        println(n.Data)
    }

    s.Children().Each(func(_ int, s *goquery.Selection) {
        getTagName(s)
    })
}

func main() {
    doc, _ := goquery.NewDocument("https://news.ycombinator.com/")
    doc.Find("html body").Children().Each(func(_ int, s *goquery.Selection) {
        getTagName(s)
    })
}

Having getTagName(s.Children()) inside the loop was causing trouble.