resources: Add JavaScript transpiling solution

Add a new pipe called TranspileJS which uses the Babel cli. This makes it possible for users to write ES6 JavaScript code and transpile it to ES5 during website generation so that the code still works with older browser versions.

Fixes #5764

2 files changed, 43 insertions, 15 deletions

diff --git a/tpl/resources/init.go b/tpl/resources/init.go
index 3e750f325..10e8e5319 100644
--- a/tpl/resources/init.go
+++ b/tpl/resources/init.go
@@ -60,6 +60,11 @@ func init() {
 			[][2]string{},
 		)
 
+		ns.AddMethodMapping(ctx.TranspileJS,
+			[]string{"transpileJS"},
+			[][2]string{},
+		)
+
 		return ns
 
 	}
diff --git a/tpl/resources/resources.go b/tpl/resources/resources.go
index 90fb58b4b..c256fa903 100644
--- a/tpl/resources/resources.go
+++ b/tpl/resources/resources.go
@@ -34,6 +34,7 @@ import (
 	"github.com/gohugoio/hugo/resources/resource_transformers/postcss"
 	"github.com/gohugoio/hugo/resources/resource_transformers/templates"
 	"github.com/gohugoio/hugo/resources/resource_transformers/tocss/scss"
+	"github.com/gohugoio/hugo/resources/resource_transformers/transpilejs"
 	"github.com/spf13/cast"
 )
 
@@ -54,14 +55,15 @@ func New(deps *deps.Deps) (*Namespace, error) {
 	}
 
 	return &Namespace{
-		deps:            deps,
-		scssClient:      scssClient,
-		createClient:    create.New(deps.ResourceSpec),
-		bundlerClient:   bundler.New(deps.ResourceSpec),
-		integrityClient: integrity.New(deps.ResourceSpec),
-		minifyClient:    minifyClient,
-		postcssClient:   postcss.New(deps.ResourceSpec),
-		templatesClient: templates.New(deps.ResourceSpec, deps),
+		deps:              deps,
+		scssClient:        scssClient,
+		createClient:      create.New(deps.ResourceSpec),
+		bundlerClient:     bundler.New(deps.ResourceSpec),
+		integrityClient:   integrity.New(deps.ResourceSpec),
+		minifyClient:      minifyClient,
+		postcssClient:     postcss.New(deps.ResourceSpec),
+		templatesClient:   templates.New(deps.ResourceSpec, deps),
+		transpileJSClient: transpilejs.New(deps.ResourceSpec),
 	}, nil
 }
 
@@ -69,13 +71,14 @@ func New(deps *deps.Deps) (*Namespace, error) {
 type Namespace struct {
 	deps *deps.Deps
 
-	createClient    *create.Client
-	bundlerClient   *bundler.Client
-	scssClient      *scss.Client
-	integrityClient *integrity.Client
-	minifyClient    *minifier.Client
-	postcssClient   *postcss.Client
-	templatesClient *templates.Client
+	createClient      *create.Client
+	bundlerClient     *bundler.Client
+	scssClient        *scss.Client
+	integrityClient   *integrity.Client
+	minifyClient      *minifier.Client
+	postcssClient     *postcss.Client
+	transpileJSClient *transpilejs.Client
+	templatesClient   *templates.Client
 }
 
 // Get locates the filename given in Hugo's assets filesystem
@@ -277,6 +280,26 @@ func (ns *Namespace) PostCSS(args ...interface{}) (resource.Resource, error) {
 
 func (ns *Namespace) PostProcess(r resource.Resource) (postpub.PostPublishedResource, error) {
 	return ns.deps.ResourceSpec.PostProcess(r)
+
+}
+
+// TranspileJS processes the given Resource with Babel.
+func (ns *Namespace) TranspileJS(args ...interface{}) (resource.Resource, error) {
+	r, m, err := ns.resolveArgs(args)
+	if err != nil {
+		return nil, err
+	}
+	var options transpilejs.Options
+	if m != nil {
+		options, err = transpilejs.DecodeOptions(m)
+
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return ns.transpileJSClient.Process(r, options)
+
 }
 
 // We allow string or a map as the first argument in some cases.