HeadHTML -> PreloadHTML

jaws.go

@@ -11,6 +11,7 @@ import (
 	"context"
 	"crypto/rand"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"html/template"
 	"io"
@@ -367,32 +368,26 @@ const jawsAlertStyle = `
 `
 
 // GenerateHeadHTML (re-)generates the HTML code that goes in the HEAD section, ensuring
-// that the provided scripts and stylesheets in `extra` are loaded.
+// that the provided URL resources in `extra` are loaded, along with the JaWS javascript.
 //
 // You only need to call this if you want to add your own scripts and stylesheets.
-func (jw *Jaws) GenerateHeadHTML(extra ...string) error {
-	var js, css []string
-	addedJaws := false
-	for _, e := range extra {
-		if u, err := url.Parse(e); err == nil {
-			if strings.HasSuffix(u.Path, ".js") {
-				js = append(js, e)
-				addedJaws = addedJaws || strings.HasSuffix(u.Path, JavascriptPath)
-			} else if strings.HasSuffix(e, ".css") {
-				css = append(css, e)
+func (jw *Jaws) GenerateHeadHTML(extra ...string) (err error) {
+	var jawsurl *url.URL
+	if jawsurl, err = url.Parse(JavascriptPath); err == nil {
+		var urls []*url.URL
+		urls = append(urls, jawsurl)
+		for _, urlstr := range extra {
+			if u, e := url.Parse(urlstr); e == nil {
+				if !strings.HasSuffix(u.Path, jawsurl.Path) {
+					urls = append(urls, u)
+				}
 			} else {
-				return fmt.Errorf("%q: not .js or .css", u.Path)
+				err = errors.Join(e)
 			}
-		} else {
-			return err
 		}
+		jw.headPrefix = PreloadHTML(urls...) + jawsAlertStyle + `<script>var jawsKey="`
 	}
-	if !addedJaws {
-		js = append(js, JavascriptPath)
-	}
-	jw.headPrefix = HeadHTML(js, css) + jawsAlertStyle + `<script>var jawsKey="`
-
-	return nil
+	return
 }
 
 // Broadcast sends a message to all Requests.

jaws_test.go

@@ -452,18 +452,22 @@ func TestJaws_subscribeOnClosedReturnsNil(t *testing.T) {
 func TestJaws_GenerateHeadHTML(t *testing.T) {
 	const extraScript = "someExtraScript.js?disregard"
 	const extraStyle = "http://other.server/someExtraStyle.css"
+	const extraImage = "someExtraImage.png"
+	const extraFont = "someExtraFont.woff2"
 	th := newTestHelper(t)
 	jw := New()
 	jw.Close()
 
-	jw.GenerateHeadHTML()
+	th.NoErr(jw.GenerateHeadHTML())
 	th.True(strings.Contains(string(jw.headPrefix), JavascriptPath))
-	jw.GenerateHeadHTML(extraScript, extraStyle)
+
+	th.NoErr(jw.GenerateHeadHTML(extraScript, extraStyle, extraImage, extraFont))
 	th.True(strings.Contains(string(jw.headPrefix), JavascriptPath))
 	th.True(strings.Contains(string(jw.headPrefix), extraScript))
 	th.True(strings.Contains(string(jw.headPrefix), extraStyle))
+	th.True(strings.Contains(string(jw.headPrefix), extraImage))
+	th.True(strings.Contains(string(jw.headPrefix), extraFont))
 
-	th.True(jw.GenerateHeadHTML("random.crap") != nil)
 	th.True(jw.GenerateHeadHTML("\n") != nil)
 }
 

js.go

@@ -5,6 +5,9 @@ import (
 	"compress/gzip"
 	_ "embed"
 	"hash/fnv"
+	"mime"
+	"net/url"
+	"path/filepath"
 	"strconv"
 	"strings"
 )
@@ -61,36 +64,66 @@ func JawsKeyValue(jawsKey string) uint64 {
 	return 0
 }
 
-const jsLoader = `.forEach(function(c){var e=document.createElement("script");e.src=c;e.async=!1;document.head.appendChild(e);});`
-
-// HeadHTML returns HTML code to load the given scripts and CSS files efficiently.
-func HeadHTML(js []string, css []string) string {
-	var s []byte
-
-	for _, e := range css {
-		s = append(s, "<link rel=\"preload\" href="...)
-		s = strconv.AppendQuote(s, e)
-		s = append(s, " as=\"style\">\n"...)
-	}
-	for _, e := range js {
-		s = append(s, "<link rel=\"preload\" href="...)
-		s = strconv.AppendQuote(s, e)
-		s = append(s, " as=\"script\">\n"...)
+// PreloadHTML returns HTML code to load the given resources efficiently.
+func PreloadHTML(urls ...*url.URL) string {
+	var jsurls, cssurls []string
+	var buf []byte
+	for _, u := range urls {
+		var asattr string
+		ext := strings.ToLower(filepath.Ext(u.Path))
+		mimetype := mime.TypeByExtension(ext)
+		if semi := strings.IndexByte(mimetype, ';'); semi > 0 {
+			mimetype = mimetype[:semi]
+		}
+		urlstr := u.String()
+		switch ext {
+		case ".js":
+			jsurls = append(jsurls, urlstr)
+			asattr = "script"
+		case ".css":
+			cssurls = append(cssurls, urlstr)
+			asattr = "style"
+		default:
+			if strings.HasPrefix(mimetype, "image") {
+				asattr = "image"
+			} else if strings.HasPrefix(mimetype, "font") {
+				asattr = "font"
+			}
+		}
+		buf = append(buf, `<link rel="preload" href="`...)
+		buf = append(buf, urlstr...)
+		buf = append(buf, '"')
+		if asattr != "" {
+			buf = append(buf, ` as="`...)
+			buf = append(buf, asattr...)
+			buf = append(buf, '"')
+		}
+		if mimetype != "" {
+			buf = append(buf, ` type="`...)
+			buf = append(buf, mimetype...)
+			buf = append(buf, '"')
+		}
+		buf = append(buf, ">\n"...)
 	}
-	s = append(s, "<script>["...)
-	for i, e := range js {
-		if i > 0 {
-			s = append(s, ',')
+
+	if len(jsurls) > 0 {
+		buf = append(buf, `<script>[`...)
+		for i, urlstr := range jsurls {
+			if i > 0 {
+				buf = append(buf, ',')
+			}
+			buf = append(buf, '"')
+			buf = append(buf, urlstr...)
+			buf = append(buf, '"')
 		}
-		s = strconv.AppendQuote(s, e)
+		buf = append(buf, "].forEach(function(c){var e=document.createElement(\"script\");e.src=c;e.async=!1;document.head.appendChild(e);});</script>\n"...)
 	}
-	s = append(s, "]"+jsLoader+"</script>\n"...)
 
-	for _, e := range css {
-		s = append(s, "<link rel=\"stylesheet\" href="...)
-		s = strconv.AppendQuote(s, e)
-		s = append(s, ">\n"...)
+	for _, urlstr := range cssurls {
+		buf = append(buf, `<link rel="stylesheet" href="`...)
+		buf = append(buf, urlstr...)
+		buf = append(buf, "\">\n"...)
 	}
 
-	return string(s)
+	return string(buf)
 }

js_test.go

@@ -5,6 +5,7 @@ import (
 	"compress/gzip"
 	_ "embed"
 	"hash/fnv"
+	"net/url"
 	"strconv"
 	"strings"
 	"testing"
@@ -32,18 +33,38 @@ func Test_Javascript(t *testing.T) {
 	th.Equal(b.Bytes(), JavascriptGZip)
 }
 
-func Test_HeadHTML(t *testing.T) {
+func Test_PreloadHTML(t *testing.T) {
 	const extraScript = "someExtraScript.js"
 	const extraStyle = "someExtraStyle.css"
+	const extraImage = "someExtraImage.png"
+	const extraFont = "someExtraFont.woff2"
 	th := newTestHelper(t)
-	txt := HeadHTML(nil, nil)
+
+	txt := PreloadHTML()
 	th.Equal(strings.Contains(txt, JavascriptPath), false)
 	th.Equal(strings.Count(txt, "<script>"), strings.Count(txt, "</script>"))
-	txt = HeadHTML([]string{JavascriptPath, extraScript}, []string{extraStyle})
+
+	mustParseUrl := func(urlstr string) *url.URL {
+		u, err := url.Parse(urlstr)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return u
+	}
+
+	txt = PreloadHTML(
+		mustParseUrl(JavascriptPath),
+		mustParseUrl(extraScript),
+		mustParseUrl(extraStyle),
+		mustParseUrl(extraImage),
+		mustParseUrl(extraFont))
 	th.Equal(strings.Contains(txt, JavascriptPath), true)
 	th.Equal(strings.Contains(txt, extraScript), true)
 	th.Equal(strings.Contains(txt, extraStyle), true)
+	th.Equal(strings.Contains(txt, extraImage), true)
+	th.Equal(strings.Contains(txt, extraFont), true)
 	th.Equal(strings.Count(txt, "<script>"), strings.Count(txt, "</script>"))
+	t.Log(txt)
 }
 
 func TestJawsKeyString(t *testing.T) {