Few more small performance tweaks

mithril.js

@@ -539,7 +539,8 @@
 		if (!keysDiffer) {
 			forKeys(inst.data, function (attrs, i) {
 				var cachedCell = inst.cached[i]
-				return keysDiffer = cachedCell &&
+				return keysDiffer =
+					cachedCell &&
 					cachedCell.attrs &&
 					cachedCell.attrs.key !== attrs.key
 			})
@@ -601,8 +602,7 @@
 
 			case MOVE:
 				var changeElement = change.element
-				if (inst.parent.childNodes[index] !== changeElement &&
-						changeElement !== null) {
+				if (inst.parent.childNodes[index] !== changeElement) {
 					inst.parent.insertBefore(
 						changeElement,
 						inst.parent.childNodes[index] || null
@@ -764,7 +764,7 @@
 
 		if (index > -1) {
 			return cached[index]
-		} else if (typeof controller === "function") {
+		} else if (isFunction(controller)) {
 			return new controller()
 		} else {
 			return {}
@@ -790,14 +790,19 @@
 		}
 	}
 
-	// shallow array compare, sorts
+	// Shallow array compare, assumes strings
 	function arraySortCompare(a, b) {
-		a.sort()
-		b.sort()
 		var len = a.length
 		if (len !== b.length) return false
-		for (var i = 0; i < len; i++) {
-			if (a[i] !== b[i]) return false
+
+		// A string-integer map is used to simplify the algorithm from
+		// two `O(n * log(n))` loops + an `O(n)` loop to just two O(n) loops
+		// with constant-time (or a super cheap `log(n)`) string key lookup.
+		var i = 0
+		var cache = Object.create(null)
+		while (i < len) cache[b[i]] = i++
+		while (i !== 0) {
+			if (cache[a[--i]] === undefined) return false
 		}
 		return true
 	}
@@ -858,8 +863,7 @@
 				return $document.createElement(data.tag)
 			}
 		} else if (data.attrs.is) {
-			return $document.createElementNS(inst.ns, data.tag,
-				data.attrs.is)
+			return $document.createElementNS(inst.ns, data.tag, data.attrs.is)
 		} else {
 			return $document.createElementNS(inst.ns, data.tag)
 		}
@@ -893,7 +897,7 @@
 
 	function objectBuildChildren(inst, node) {
 		var children = inst.builder.data.children
-		if (children != null && children.length !== 0) {
+		if (children != null && children.length) {
 			return objectMakeChild(inst, node, true)
 		} else {
 			return children
@@ -995,22 +999,8 @@
 	}
 
 	function nodeHasBody(node) {
-		return node !== "AREA" &&
-			node !== "BASE" &&
-			node !== "BR" &&
-			node !== "COL" &&
-			node !== "COMMAND" &&
-			node !== "EMBED" &&
-			node !== "HR" &&
-			node !== "IMG" &&
-			node !== "INPUT" &&
-			node !== "KEYGEN" &&
-			node !== "LINK" &&
-			node !== "META" &&
-			node !== "PARAM" &&
-			node !== "SOURCE" &&
-			node !== "TRACK" &&
-			node !== "WBR"
+		return !/^(AREA|BASE|BR|COL|COMMAND|EMBED|HR|IMG|INPUT|KEYGEN|LINK|META|PARAM|SOURCE|TRACK|WBR)$/ // eslint-disable-line max-len
+			.test(node)
 	}
 
 	function builderHandleNonexistentNodes(inst) {
@@ -1053,10 +1043,9 @@
 				inst.editable.innerHTML = inst.data
 			} else {
 				// was a trusted string
-				if (nodes[0].nodeType === 1 ||
-					nodes.length > 1 ||
-					(nodes[0].nodeValue.trim && !nodes[0].nodeValue.trim())
-				) {
+				if (nodes[0].nodeType === 1 || nodes.length > 1 ||
+					isString(nodes[0].nodeValue) &&
+						/\s*/.test(nodes[0].nodeValue)) {
 					clear(inst.cached.nodes, inst.cached)
 					nodes = [$document.createTextNode(inst.data)]
 				}
@@ -1112,12 +1101,7 @@
 	}
 
 	function shouldSetAttrDirectly(attr) {
-		return attr !== "list" &&
-			attr !== "style" &&
-			attr !== "form" &&
-			attr !== "type" &&
-			attr !== "width" &&
-			attr !== "height"
+		return !/^(list|style|form|type|width|height)$/.test(attr)
 	}
 
 	function trySetAttribute(attr, dataAttr, cachedAttr, node, namespace, tag) {
@@ -1159,7 +1143,7 @@
 			//   used as a string, but it's an object in js
 			//
 			// #348
-			// don't set the value if not needed otherwise cursor placement
+			// don't set the value if not needed, otherwise cursor placement
 			// breaks in Chrome
 			if (tag !== "input" || node[attr] !== dataAttr) {
 				node[attr] = dataAttr
@@ -1175,7 +1159,7 @@
 		} catch (e) {
 			// swallow IE's invalid argument errors to mimic HTML's
 			// fallback-to-doing-nothing-on-invalid-attributes behavior
-			if (e.message.indexOf("Invalid argument") < 0) throw e
+			if (!/\bInvalid argument\b/.test(e.message)) throw e
 		}
 	}
 
@@ -1187,7 +1171,7 @@
 				trySetSingle(attr, dataAttr, cachedAttr, node, namespace, tag)
 			} else if (attr === "value" && tag === "input" &&
 					// #348: dataAttr may not be a string, so use loose
-					// comparison
+					// comparison (i.e. identity not required).
 					node.value != dataAttr) { // eslint-disable-line eqeqeq
 				node.value = dataAttr
 			}
@@ -1362,7 +1346,7 @@
 
 	function getCellCacheKey(element) {
 		var index = nodeCache.indexOf(element)
-		return index < 0 ? nodeCache.push(element) - 1 : index
+		return index >= 0 ? index : nodeCache.push(element) - 1
 	}
 
 	m.trust = function (value) {
@@ -1468,7 +1452,7 @@
 	var lastRedrawCallTime = 0
 
 	function actuallyPerformRedraw() {
-		if (lastRedrawId > 0) $cancelAnimationFrame(lastRedrawId)
+		if (lastRedrawId !== 0) $cancelAnimationFrame(lastRedrawId)
 		lastRedrawId = $requestAnimationFrame(redraw, FRAME_BUDGET)
 	}
 
@@ -1830,8 +1814,8 @@
 	}
 
 	function parseQueryString(str) {
-		if (str === "" || str == null) return {}
-		if (str.charAt(0) === "?") str = str.slice(1)
+		if (!str) return {}
+		if (str[0] === "?") str = str.slice(1)
 
 		var pairs = str.split("&")
 		var params = {}
@@ -2136,7 +2120,7 @@
 
 		script.src = options.url +
 			(options.url.indexOf("?") > 0 ? "&" : "?") +
-			(options.callbackKey ? options.callbackKey : "callback") +
+			(options.callbackKey || "callback") +
 			"=" + callbackKey +
 			"&" + buildQueryString(options.data || {})
 
@@ -2183,7 +2167,7 @@
 			data = options.data
 		}
 
-		if (data && !isString(data) && data.constructor !== window.FormData) {
+		if (data && !isString(data) && !(data instanceof window.FormData)) {
 			throw new Error("Request data should be either be a string or " +
 				"FormData. Check the `serialize` option in `m.request`")
 		}
@@ -2193,7 +2177,7 @@
 	}
 
 	function ajax(options) {
-		if (options.dataType && options.dataType.toLowerCase() === "jsonp") {
+		if (options.dataType === "JSONP") {
 			return getJsonp(options)
 		} else {
 			return runXhr(options)
@@ -2235,15 +2219,15 @@
 			return jsonp.responseText
 		}
 
-		if (!options.dataType || options.dataType.toLowerCase() !== "jsonp") {
+		if (!options.dataType || options.dataType.toUpperCase() !== "JSONP") {
+			options.dataType = "JSONP"
 			serialize = options.serialize || JSON.stringify
 			deserialize = options.deserialize || JSON.parse
 			extract = options.extract || function (xhr) {
-				if (xhr.responseText.length === 0 &&
-						deserialize === JSON.parse) {
-					return null
-				} else {
+				if (xhr.responseText.length || deserialize !== JSON.parse) {
 					return xhr.responseText
+				} else {
+					return null
 				}
 			}
 		}