single vm per build

extender.go

@@ -1,24 +1,33 @@
 package katex
 
 import (
+	_ "embed"
+
 	"github.com/bluele/gcache"
+	"github.com/dop251/goja"
 	"github.com/yuin/goldmark"
 	"github.com/yuin/goldmark/parser"
 	"github.com/yuin/goldmark/renderer"
 	"github.com/yuin/goldmark/util"
 )
 
+//go:embed katex.min.js
+var katexjs string
+
 type Extender struct {
 }
 
 func (e *Extender) Extend(m goldmark.Markdown) {
+	vm := goja.New()
+	vm.RunString(katexjs)
 	m.Parser().AddOptions(parser.WithInlineParsers(
 		util.Prioritized(&Parser{}, 0),
 	))
 	m.Renderer().AddOptions(renderer.WithNodeRenderers(
 		util.Prioritized(&HTMLRenderer{
 			cacheInline:  gcache.New(5000).ARC().Build(),
 			cacheDisplay: gcache.New(5000).ARC().Build(),
+			gojaVM:       vm,
 		}, 0),
 	))
 }

katex.go

@@ -1,25 +1,15 @@
 package katex
 
 import (
-	_ "embed"
 	"io"
 
 	"github.com/dop251/goja"
 )
 
-//go:embed katex.min.js
-var katexjs string
-
-func Render(w io.Writer, src []byte, display bool) error {
+func Render(w io.Writer, src []byte, display bool, vm *goja.Runtime) error {
 	var res goja.Value
-	vm := goja.New()
-
-	_, err := vm.RunString(katexjs)
-	if err != nil {
-		return err
-	}
 
-	err = vm.Set("expression", string(src))
+	err := vm.Set("expression", string(src))
 	if err != nil {
 		return nil
 	}

katex_test.go

@@ -4,11 +4,13 @@ import (
 	"bytes"
 	"fmt"
 	"testing"
+
+	"github.com/dop251/goja"
 )
 
 func ExampleRender() {
 	b := bytes.Buffer{}
-	Render(&b, []byte(`Y = A \dot X^2 + B \dot X + C`), false)
+	Render(&b, []byte(`Y = A \dot X^2 + B \dot X + C`), false, goja.New())
 	fmt.Println(b.String())
 
 	// Output:
@@ -18,6 +20,6 @@ func ExampleRender() {
 func BenchmarkRender(b *testing.B) {
 	for n := 0; n < b.N; n++ {
 		b := bytes.Buffer{}
-		Render(&b, []byte(`Y = A \dot X^2 + B \dot X + C`), false)
+		Render(&b, []byte(`Y = A \dot X^2 + B \dot X + C`), false, goja.New())
 	}
 }

renderer.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 
 	"github.com/bluele/gcache"
+	"github.com/dop251/goja"
 	"github.com/yuin/goldmark/ast"
 	"github.com/yuin/goldmark/renderer"
 	"github.com/yuin/goldmark/renderer/html"
@@ -15,6 +16,7 @@ type HTMLRenderer struct {
 
 	cacheInline  gcache.Cache
 	cacheDisplay gcache.Cache
+	gojaVM       *goja.Runtime
 }
 
 func (r *HTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
@@ -35,7 +37,7 @@ func (r *HTMLRenderer) renderInline(w util.BufWriter, source []byte, n ast.Node,
 
 		if err == gcache.KeyNotFoundError {
 			b := bytes.Buffer{}
-			err = Render(&b, node.Equation, false)
+			err = Render(&b, node.Equation, false, r.gojaVM)
 			if err != nil {
 				return ast.WalkStop, err
 			}
@@ -64,7 +66,7 @@ func (r *HTMLRenderer) renderBlock(w util.BufWriter, source []byte, n ast.Node,
 
 		if err == gcache.KeyNotFoundError {
 			b := bytes.Buffer{}
-			err = Render(&b, node.Equation, true)
+			err = Render(&b, node.Equation, true, r.gojaVM)
 			if err != nil {
 				return ast.WalkStop, err
 			}