Support for skipping redraws (#1049)

Mostly useful for event handlers, setting `e.redraw = false` will prevent mithril from re-rendering.

api/tests/test-mount.js

@@ -77,6 +77,38 @@ o.spec("m.mount", function() {
 		}, FRAME_BUDGET)
 	})
 	
+	o("event handlers can skip redraw", function(done) {
+		var onupdate = o.spy()
+		var oninit   = o.spy()
+		var mount = createMounter($window, {})
+		var e = $window.document.createEvent("MouseEvents")
+		
+		e.initEvent("click", true, true)
+		
+		mount(root, {
+			view: function() {
+				return m("div", {
+					oninit: oninit,
+					onupdate: onupdate,
+					onclick: function(e) {
+						e.redraw = false
+					}
+				})
+			}
+		})
+		
+		root.firstChild.dispatchEvent(e)
+		
+		o(oninit.callCount).equals(1)
+		
+		// Wrapped to ensure no redraw fired
+		setTimeout(function() {
+			o(onupdate.callCount).equals(0)
+			
+			done()
+		}, 20)
+	})
+	
 	 o("redraws on redraw.run()", function(done) {
 		var onupdate = o.spy()
 		var oninit = o.spy()

api/tests/test-router.js

@@ -114,6 +114,40 @@ o.spec("m.route", function() {
 		}, FRAME_BUDGET)
 	})
 	
+	o("event handlers can skip redraw", function(done) {
+		var onupdate = o.spy()
+		var oninit   = o.spy()
+		var onclick  = o.spy()
+		var e = $window.document.createEvent("MouseEvents")
+		
+		e.initEvent("click", true, true)
+		
+		route(root, "/", {
+			"/" : {
+				view: function() {
+					return m("div", {
+						oninit: oninit,
+						onupdate: onupdate,
+						onclick: function(e) {
+							e.redraw = false
+						},
+					})
+				}
+			}
+		})
+		
+		root.firstChild.dispatchEvent(e)
+		
+		o(oninit.callCount).equals(1)
+		
+		// Wrapped to ensure no redraw fired
+		setTimeout(function() {
+			o(onupdate.callCount).equals(0)
+			
+			done()
+		}, 20)
+	})
+	
 	o("changes location on route.link", function() {
 		var e = $window.document.createEvent("MouseEvents")
 		

api/tests/test-throttle.js

@@ -81,4 +81,12 @@ o.spec("throttle", function() {
 		
 		o(spy.callCount).equals(2)
 	})
-})
+	
+	o("it supports aborting when redraw is falsey", function() {
+		throttled({ redraw : false })
+		throttled({ redraw : 0 })
+		throttled({ redraw : "" })
+		
+		o(spy.callCount).equals(0)
+	})
+})

api/throttle.js

@@ -7,6 +7,7 @@ module.exports = function(callback) {
 	var timeout = typeof requestAnimationFrame === "function" ? requestAnimationFrame : setTimeout
 	return function(synchronous) {
 		var now = new Date().getTime()
+		if (typeof synchronous === "object" && "redraw" in synchronous && !synchronous.redraw) return
 		if (synchronous === true || last === 0 || now - last >= time) {
 			last = now
 			callback()