feat: improve real-time chart example; add small refinements to via core files

actiontrigger.go

@@ -12,7 +12,13 @@ type actionTrigger struct {
 }
 
 // OnClick returns a via.h DOM node that triggers on click. It can be added
-// to other nodes in a view.
+// to element nodes in a view.
 func (a *actionTrigger) OnClick() h.H {
 	return h.Data("on:click", fmt.Sprintf("@get('/_action/%s')", a.id))
 }
+
+// OnChange returns a via.h DOM node that triggers on input change. It can be added
+// to element nodes in a view.
+func (a *actionTrigger) OnChange() h.H {
+	return h.Data("on:change__debounce.200ms", fmt.Sprintf("@get('/_action/%s')", a.id))
+}

h/attributes.go

@@ -34,6 +34,10 @@ func Class(v string) H {
 	return gh.Class(v)
 }
 
+func Role(v string) H {
+	return gh.Role(v)
+}
+
 // Data attributes automatically have their name prefixed with "data-".
 func Data(name, v string) H {
 	return gh.Data(name, v)

h/h.go

@@ -11,6 +11,7 @@ package h
 
 import (
 	"io"
+
 	g "maragu.dev/gomponents"
 	gc "maragu.dev/gomponents/components"
 )
@@ -50,6 +51,13 @@ func Attr(name string, value ...string) H {
 	return g.Attr(name, value...)
 }
 
+func If(condition bool, n H) H {
+	if condition {
+		return n
+	}
+	return nil
+}
+
 // HTML5Props defines properties for HTML5 pages. Title is set always set, Description
 // and Language elements only if the strings are non-empty.
 type HTML5Props struct {

h/util.go

@@ -7,6 +7,10 @@ import (
 func retype(nodes []H) []g.Node {
 	list := make([]g.Node, len(nodes))
 	for i, node := range nodes {
+		if node == nil {
+			list[i] = nil
+			continue
+		}
 		list[i] = node.(g.Node)
 	}
 	return list

internal/examples/realtimechart/main.go

@@ -38,33 +38,47 @@ func chartCompFn(c *via.Context) {
 	data := make([]float64, 1000)
 	labels := make([]string, 1000)
 
+	isLive := false
+	refreshRate := c.Signal(1)
+	tkr := time.NewTicker(1000 * time.Millisecond)
+
+	updateRefreshRate := c.Action(func() {
+		tkr.Reset(1000 / time.Duration(refreshRate.Int()) * time.Millisecond)
+	})
+
+	toggleIsLive := c.Action(func() {
+		isLive = !isLive
+	})
+
 	go func() {
-		tkr := time.NewTicker(60 * time.Millisecond)
 		defer tkr.Stop()
 		for range tkr.C {
 			labels = append(labels[1:], time.Now().Format("15:04:05.000"))
-			data = append(data[1:], rand.Float64()*1000)
+			data = append(data[1:], rand.Float64()*10)
 			labelsTxt, _ := json.Marshal(labels)
 			dataTxt, _ := json.Marshal(data)
 
+			if isLive {
 				c.ExecScript(fmt.Sprintf(`
 			if (myChart)
 				myChart.setOption({
 					xAxis: [{data: %s}],
 					series:[{data: %s}]
-				});
+				},{notMerge:false,lazyUpdate:true});
 			`, labelsTxt, dataTxt))
 			}
+		}
 	}()
 
 	c.View(func() h.H {
-		return h.Div(h.ID("chart"), h.Style("width:100%;height:400px;"),
+		return h.Div(
+			h.Div(h.ID("chart"), h.Style("width:100%;height:400px;"),
 				h.Script(h.Raw(`
 				const prefersDark = window.matchMedia('(prefers-color-scheme: dark)');
 				var myChart = echarts.init(document.getElementById('chart'), prefersDark.matches ? 'dark' : 'light');
 				var option = {
 					backgroundColor: prefersDark.matches ? 'transparent' : '#ffffff',
-					animationDurationUpdate: 60,  //  affects updates/redraws
+					animationDurationUpdate: 0,  //  affects updates/redraws
 					tooltip: {
 						trigger: 'axis',
 						position: function (pt) {
@@ -75,15 +89,6 @@ func chartCompFn(c *via.Context) {
 						left: 'center',
 						text: 'Large Area Chart'
 					},
-					toolbox: {
-						feature: {
-							dataZoom: {
-								yAxisIndex: 'none'
-							},
-							restore: {},
-							saveAsImage: {}
-						}
-					},
 					xAxis: {
 						type: 'category',
 						boundaryGap: false,
@@ -131,6 +136,22 @@ func chartCompFn(c *via.Context) {
 				};
 				option && myChart.setOption(option);
 			`)),
+				h.Section(
+					h.Article(
+						h.H5(h.Text("Controls")),
+						h.Hr(),
+						h.Div(h.Class("grid"),
+							h.FieldSet(
+								h.Legend(h.Text("Live Data")),
+								h.Input(h.Type("checkbox"), h.Role("switch"), toggleIsLive.OnChange()),
+							),
+							h.Label(h.ID("refresh-rate-input"), h.Span(h.Text("Refresh Rate  (")), h.Span(refreshRate.Text()), h.Span(h.Text(" Hz)")),
+								h.Input(h.Type("range"), h.Attr("min", "1"), h.Attr("max", "200"), refreshRate.Bind(), updateRefreshRate.OnChange()),
+							),
+						),
+					),
+				),
+			),
 		)
 	})
 }

signal.go

@@ -49,7 +49,7 @@ func (s *signal) Bind() h.H {
 //
 // Example:
 //
-//	h.Div(h.Text("x: "), mysignal.Text())
+//	h.Div(mysignal.Text())
 func (s *signal) Text() h.H {
 	return h.Data("text", "$"+s.id)
 }

via.go

@@ -106,7 +106,7 @@ func (v *via) Page(route string, composeContext func(c *Context)) {
 		headElements := v.cfg.DocumentHeadIncludes
 		headElements = append(headElements, h.Meta(h.Data("signals", fmt.Sprintf("{'via-ctx':'%s'}", id))))
 		headElements = append(headElements, h.Meta(h.Data("init", "@get('/_sse')")))
-		bottomBodyElements := []h.H{h.Div(h.ID(c.id), c.view())}
+		bottomBodyElements := []h.H{c.view()}
 		for _, el := range v.cfg.DocumentBodyIncludes {
 			bottomBodyElements = append(bottomBodyElements, el)
 		}