Advanced Usage
Custom Scorer
Customize content recognition logic for specific website structures. See Testing & Custom Extensions for the full implementation. Here's the core usage:
go
package main
import (
"fmt"
"log"
"strings"
"github.com/cybergodev/html"
)
// Implement custom Scorer (full example in guides/testing-custom)
type myScorer struct{}
func (s myScorer) Score(node html.ContentNode) int {
if node == nil {
return 0
}
class := node.AttrValue("class")
if strings.Contains(class, "article") || strings.Contains(class, "post") {
return 100
}
if strings.Contains(class, "sidebar") || strings.Contains(class, "comment") {
return -50
}
return 0
}
func (s myScorer) ShouldRemove(node html.ContentNode) bool {
switch node.Data() {
case "nav", "footer", "header":
return true
}
return false
}
func main() {
cfg := html.DefaultConfig()
cfg.Scorer = myScorer{}
p, err := html.New(cfg)
if err != nil {
log.Fatal(err)
}
defer p.Close()
data := []byte(`<html><body>
<nav><a href="/">Home</a></nav>
<article class="post-content">
<h1>Understanding Go Concurrency</h1>
<p>Goroutines are Go's lightweight threads.</p>
</article>
<aside class="sidebar">Recommended Reading</aside>
</body></html>`)
result, err := p.Extract(data)
if err != nil {
log.Fatal(err)
}
fmt.Println("Text:", result.Text)
// Text: Understanding Go Concurrency
//
// Goroutines are Go's lightweight threads.
}Multi-Sink Audit Pipeline
Build a tiered audit pipeline: critical events go to a separate file, all events also output to logs.
go
package main
import (
"fmt"
"log"
"os"
"github.com/cybergodev/html"
)
func main() {
// Create output destinations
allFile, _ := os.Create("audit-all.jsonl")
criticalFile, _ := os.Create("audit-critical.jsonl")
defer allFile.Close()
defer criticalFile.Close()
// Build multi-tier pipeline
allSink := html.NewWriterAuditSink(allFile)
criticalSink := html.NewFilteredSink(
html.NewWriterAuditSink(criticalFile),
func(e html.AuditEntry) bool {
return e.Level == html.AuditLevelCritical
},
)
loggerSink := html.NewLoggerAuditSink()
pipeline := html.NewMultiSink(allSink, criticalSink, loggerSink)
// Configuration
cfg := html.HighSecurityConfig()
cfg.Audit = html.HighSecurityAuditConfig()
cfg.Audit.Sink = pipeline
p, err := html.New(cfg)
if err != nil {
log.Fatal(err)
}
defer p.Close()
// Process content
data := []byte(`<html><body>
<script>alert('xss')</script>
<article><p>Safe content</p></article>
</body></html>`)
result, err := p.Extract(data)
if err != nil {
log.Fatal(err)
}
fmt.Println("Text:", result.Text)
// Audit logs automatically recorded to files and stderr
}Batch File Processing
Process HTML files in a directory, collecting results and errors:
go
package main
import (
"fmt"
"os"
"path/filepath"
"github.com/cybergodev/html"
)
func main() {
// Collect file paths
var files []string
filepath.Walk("./pages", func(path string, info os.FileInfo, err error) error {
if err != nil {
return nil
}
if filepath.Ext(path) == ".html" || filepath.Ext(path) == ".htm" {
files = append(files, path)
}
return nil
})
fmt.Printf("Found %d files\n", len(files))
// Batch process
p, _ := html.New(html.TextOnlyConfig())
defer p.Close()
// single batch limit 10000; exceeding it fails the whole batch — caller must chunk
batch := p.ExtractBatchFiles(files)
fmt.Printf("Success: %d, Failed: %d, Cancelled: %d\n",
batch.Success, batch.Failed, batch.Cancelled)
// Process results
for i, result := range batch.Results {
if result != nil {
fmt.Printf("[%d] %s (words: %d)\n", i, result.Title, result.WordCount)
}
}
// Check errors
for i, err := range batch.Errors {
if err != nil {
fmt.Printf("[%d] Error: %v\n", i, err)
}
}
}Processor Reuse with Timeout
Processor singleton pattern for web service scenarios:
go
package main
import (
"context"
"encoding/json"
"fmt"
"log"
"net/http"
"time"
"github.com/cybergodev/html"
)
var processor *html.Processor
func init() {
cfg := html.DefaultConfig()
cfg.MaxCacheEntries = 5000
cfg.CacheTTL = 30 * time.Minute
cfg.ProcessingTimeout = 10 * time.Second
var err error
processor, err = html.New(cfg)
if err != nil {
log.Fatal(err)
}
}
func extractHandler(w http.ResponseWriter, r *http.Request) {
ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
defer cancel()
data := []byte(r.FormValue("html"))
if len(data) == 0 {
http.Error(w, "html field required", http.StatusBadRequest)
return
}
result, err := processor.ExtractWithContext(ctx, data)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "application/json")
json.NewEncoder(w).Encode(result)
}
func statsHandler(w http.ResponseWriter, r *http.Request) {
stats := processor.GetStatistics()
fmt.Fprintf(w, "Processed: %d\nCache hits: %d\nErrors: %d\n",
stats.TotalProcessed, stats.CacheHits, stats.ErrorCount)
}
func main() {
defer processor.Close()
http.HandleFunc("/extract", extractHandler)
http.HandleFunc("/stats", statsHandler)
log.Fatal(http.ListenAndServe(":8080", nil))
}Extract and Generate Markdown Files
Extract content from HTML pages and save as Markdown:
go
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/cybergodev/html"
)
func main() {
p, err := html.New(html.MarkdownConfig())
if err != nil {
log.Fatal(err)
}
defer p.Close()
urls := []string{
"downloaded/page1.html",
"downloaded/page2.html",
"downloaded/page3.html",
}
for _, path := range urls {
md, err := p.ExtractToMarkdownFromFile(path)
if err != nil {
log.Printf("Failed to process %s: %v", path, err)
continue
}
// Generate output filename
outPath := strings.Replace(path, ".html", ".md", 1)
if err := os.WriteFile(outPath, []byte(md), 0644); err != nil {
log.Printf("Failed to write %s: %v", outPath, err)
continue
}
fmt.Printf("✓ %s → %s\n", path, outPath)
}
}