godoc: inject treeview content only when needed

- This shaves off 12.8KB (unzipped) / 3.8KB (zipped)
downloadable data and around 6ms of javascript parse time
when the files are not injected.

- Also, conditionally rendering the callgraph html only when
callgraph is actually present.

- Removed the "text/javascript" attribute as it is the default
value now.

Change-Id: I70c030bdda2a054c181b2b3a693842bafed88d1a
Reviewed-on: https://go-review.googlesource.com/c/115875
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

godoc/page.go

@@ -23,6 +23,7 @@ type Page struct {
 	Query    string
 	Body     []byte
 	GoogleCN bool // page is being served from golang.google.cn
+	TreeView bool // page needs to contain treeview related js and css
 
 	// filled in by ServePage
 	SearchBox       bool

godoc/server.go

@@ -315,6 +315,7 @@ func (h *handlerServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// Emit JSON array for type information.
 	pi := h.c.Analysis.PackageInfo(relpath)
+	hasTreeView := len(pi.CallGraph) != 0
 	info.CallGraphIndex = pi.CallGraphIndex
 	info.CallGraph = htmltemplate.JS(marshalJSON(pi.CallGraph))
 	info.AnalysisData = htmltemplate.JS(marshalJSON(pi.Types))
@@ -336,6 +337,7 @@ func (h *handlerServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		Subtitle: subtitle,
 		Body:     body,
 		GoogleCN: info.GoogleCN,
+		TreeView: hasTreeView,
 	})
 }
 

godoc/static/godoc.html

@@ -13,7 +13,9 @@
 {{if .SearchBox}}
 <link rel="search" type="application/opensearchdescription+xml" title="godoc" href="/opensearch.xml" />
 {{end}}
+{{if .TreeView}}
 <link rel="stylesheet" href="/lib/godoc/jquery.treeview.css">
+{{end}}
 <script>window.initFuncs = [];</script>
 {{with .GoogleAnalytics}}
 <script type="text/javascript">
@@ -29,8 +31,10 @@ window.trackEvent = function(category, action, opt_label, opt_value, opt_noninte
 </script>
 {{end}}
 <script src="/lib/godoc/jquery.js" defer></script>
+{{if .TreeView}}
 <script src="/lib/godoc/jquery.treeview.js" defer></script>
 <script src="/lib/godoc/jquery.treeview.edit.js" defer></script>
+{{end}}
 
 {{if .Playground}}
 <script src="/lib/godoc/playground.js" defer></script>

godoc/static/package.html

@@ -10,7 +10,7 @@
 	correspond to Go identifiers).
 -->
 {{with .PDoc}}
-	<script type='text/javascript'>
+	<script>
 	document.ANALYSIS_DATA = {{$.AnalysisData}};
 	document.CALLGRAPH = {{$.CallGraph}};
 	</script>
@@ -112,6 +112,7 @@
 		</div><!-- .expanded -->
 		</div><!-- #pkg-index -->
 
+		{{if ne $.CallGraph "null"}}
 		<div id="pkg-callgraph" class="toggle" style="display: none">
 		<div class="collapsed">
 			<h2 class="toggleButton" title="Click to show Internal Call Graph section">Internal call graph ▹</h2>
@@ -148,6 +149,7 @@
 			<ul style="margin-left: 0.5in" id="callgraph-0" class="treeview"></ul>
 		</div>
 		</div> <!-- #pkg-callgraph -->
+		{{end}}
 
 		{{with .Consts}}
 			<h2 id="pkg-constants">Constants</h2>