[refactor] Refactoring of hyperscript.js and render.js, including performance improvements

api/router.js

@@ -6,7 +6,6 @@ var m = require("../render/hyperscript")
 var buildPathname = require("../pathname/build")
 var parsePathname = require("../pathname/parse")
 var compileTemplate = require("../pathname/compileTemplate")
-var assign = require("../util/assign")
 var censor = require("../util/censor")
 
 var sentinel = {}
@@ -78,7 +77,7 @@ module.exports = function($window, mountRedraw) {
 			.slice(route.prefix.length)
 		var data = parsePathname(path)
 
-		assign(data.params, $window.history.state)
+		Object.assign(data.params, $window.history.state)
 
 		function reject(e) {
 			console.error(e)

pathname/build.js

@@ -1,7 +1,6 @@
 "use strict"
 
 var buildQueryString = require("../querystring/build")
-var assign = require("../util/assign")
 
 // Returns `path` from `template` + `params`
 module.exports = function(template, params) {
@@ -16,7 +15,7 @@ module.exports = function(template, params) {
 	var path = template.slice(0, pathEnd)
 	var query = {}
 
-	assign(query, params)
+	Object.assign(query, params)
 
 	var resolved = path.replace(/:([^\/\.-]+)(\.{3})?/g, function(m, key, variadic) {
 		delete query[key]

render/hyperscript.js

@@ -5,7 +5,7 @@ var hyperscriptVnode = require("./hyperscriptVnode")
 var hasOwn = require("../util/hasOwn")
 
 var selectorParser = /(?:(^|#|\.)([^#\.\[\]]+))|(\[(.+?)(?:\s*=\s*("|'|)((?:\\["'\]]|.)*?)\5)?\])/g
-var selectorCache = {}
+var selectorCache = Object.create(null)
 
 function isEmpty(object) {
 	for (var key in object) if (hasOwn.call(object, key)) return false
@@ -27,6 +27,7 @@ function compileSelector(selector) {
 		}
 	}
 	if (classes.length > 0) attrs.className = classes.join(" ")
+	if (isEmpty(attrs)) attrs = null
 	return selectorCache[selector] = {tag: tag, attrs: attrs}
 }
 
@@ -37,32 +38,30 @@ function execSelector(state, vnode) {
 
 	vnode.tag = state.tag
 
-	if (!isEmpty(state.attrs)) {
-		var newAttrs = {}
-
-		for (var key in attrs) {
-			if (hasOwn.call(attrs, key)) newAttrs[key] = attrs[key]
-		}
-
-		attrs = newAttrs
-	}
-
-	for (var key in state.attrs) {
-		if (hasOwn.call(state.attrs, key) && key !== "className" && !hasOwn.call(attrs, key)){
-			attrs[key] = state.attrs[key]
-		}
+	if (state.attrs != null) {
+		attrs = Object.assign({}, state.attrs, attrs)
+
+		if (className != null || state.attrs.className != null) attrs.className =
+			className != null
+				? state.attrs.className != null
+					? String(state.attrs.className) + " " + String(className)
+					: className
+				: state.attrs.className != null
+					? state.attrs.className
+					: null
+	} else {
+		if (className != null) attrs.className = className
 	}
-	if (className != null || state.attrs.className != null) attrs.className =
-		className != null
-			? state.attrs.className != null
-				? String(state.attrs.className) + " " + String(className)
-				: className
-			: state.attrs.className != null
-				? state.attrs.className
-				: null
 
 	if (hasClass) attrs.class = null
 
+	// workaround for #2622 (reorder keys in attrs to set "type" first)
+	// The DOM does things to inputs based on the "type", so it needs set first.
+	// See: https://github.com/MithrilJS/mithril.js/issues/2622
+	if (state.tag === "input" && hasOwn.call(attrs, "type")) {
+		attrs = Object.assign({type: attrs.type}, attrs)
+	}
+
 	vnode.attrs = attrs
 
 	return vnode

render/render.js

@@ -671,25 +671,20 @@ module.exports = function() {
 
 	//attrs
 	function setAttrs(vnode, attrs, ns) {
-		// If you assign an input type that is not supported by IE 11 with an assignment expression, an error will occur.
-		//
-		// Also, the DOM does things to inputs based on the value, so it needs set first.
-		// See: https://github.com/MithrilJS/mithril.js/issues/2622
-		if (vnode.tag === "input" && attrs.type != null) vnode.dom.setAttribute("type", attrs.type)
-		var isFileInput = attrs != null && vnode.tag === "input" && attrs.type === "file"
 		for (var key in attrs) {
-			setAttr(vnode, key, null, attrs[key], ns, isFileInput)
+			setAttr(vnode, key, null, attrs[key], ns)
 		}
 	}
-	function setAttr(vnode, key, old, value, ns, isFileInput) {
-		if (key === "key" || key === "is" || value == null || isLifecycleMethod(key) || (old === value && !isFormAttribute(vnode, key)) && typeof value !== "object" || key === "type" && vnode.tag === "input") return
+	function setAttr(vnode, key, old, value, ns) {
+		if (key === "key" || key === "is" || value == null || isLifecycleMethod(key) || (old === value && !isFormAttribute(vnode, key)) && typeof value !== "object") return
 		if (key[0] === "o" && key[1] === "n") return updateEvent(vnode, key, value)
 		if (key.slice(0, 6) === "xlink:") vnode.dom.setAttributeNS("http://www.w3.org/1999/xlink", key.slice(6), value)
 		else if (key === "style") updateStyle(vnode.dom, old, value)
 		else if (hasPropertyKey(vnode, key, ns)) {
 			if (key === "value") {
 				// Only do the coercion if we're actually going to check the value.
 				/* eslint-disable no-implicit-coercion */
+				var isFileInput = vnode.tag === "input" && vnode.attrs.type === "file"
 				//setting input[value] to same value by typing on focused element moves cursor to end in Chrome
 				//setting input[type=file][value] to same value causes an error to be generated if it's non-empty
 				if ((vnode.tag === "input" || vnode.tag === "textarea") && vnode.dom.value === "" + value && (isFileInput || vnode.dom === activeElement(vnode.dom))) return
@@ -702,7 +697,9 @@ module.exports = function() {
 				if (isFileInput && "" + value !== "") { console.error("`value` is read-only on file inputs!"); return }
 				/* eslint-enable no-implicit-coercion */
 			}
-			vnode.dom[key] = value
+			// If you assign an input type that is not supported by IE 11 with an assignment expression, an error will occur.
+			if (vnode.tag === "input" && key === "type") vnode.dom.setAttribute(key, value)
+			else vnode.dom[key] = value
 		} else {
 			if (typeof value === "boolean") {
 				if (value) vnode.dom.setAttribute(key, "")
@@ -750,14 +747,8 @@ module.exports = function() {
 			console.warn("Don't reuse attrs object, use new object for every redraw, this will throw in next major")
 		}
 		if (attrs != null) {
-			// If you assign an input type that is not supported by IE 11 with an assignment expression, an error will occur.
-			//
-			// Also, the DOM does things to inputs based on the value, so it needs set first.
-			// See: https://github.com/MithrilJS/mithril.js/issues/2622
-			if (vnode.tag === "input" && attrs.type != null) vnode.dom.setAttribute("type", attrs.type)
-			var isFileInput = vnode.tag === "input" && attrs.type === "file"
 			for (var key in attrs) {
-				setAttr(vnode, key, old && old[key], attrs[key], ns, isFileInput)
+				setAttr(vnode, key, old && old[key], attrs[key], ns)
 			}
 		}
 		var val