images

package main

import (
	"log"
	"os"

	images "github.com/fundipper/goldmark-images"
	"github.com/yuin/goldmark"
)

var source = []byte(`![alt](image.png "title")`)

func main() {
	md := goldmark.New(
		goldmark.WithExtensions(
			images.NewExtender(
				"/loading.gif", // source
				"data-src",     // target
				map[string]string{
					"class": "lazy", // arrtibute
				}),
		),
	)
	if err := md.Convert(source, os.Stdout); err != nil {
		log.Fatal(err)
	}

}

Output:

<p>
<img src="/loading.gif" alt="alt" title="title" class="lazy" data-src="image.png">
</p>