Revert attrs.class creation logic to what we had in v1.0.1. fix #1764

render/hyperscript.js

@@ -34,8 +34,8 @@ function execSelector(state, attrs, children) {
 		}
 	}
 
-	if (className != null) {
+	if (className !== undefined) {
-		if (attrs.class != null) {
+		if (attrs.class !== undefined) {
 			attrs.class = undefined
 			attrs.className = className
 		}

render/tests/test-hyperscript.js

@@ -16,6 +16,108 @@ o.spec("hyperscript", function() {
 
 			o(vnode.tag).equals("a")
 		})
+		o("v1.0.1 bug-for-bug regression suite", function(){
+			o
+			console.log(m('a', {
+				class: null
+			}).attrs, {
+				class: undefined,
+				className: null
+			})
+			o(m('a', {
+				class: null
+			}).attrs).deepEquals({
+				class: undefined,
+				className: null
+			})
+			o(m('a', {
+				class: undefined
+			}).attrs).deepEquals({
+				class: undefined,
+			})
+			o(m('a', {
+				class: false
+			}).attrs).deepEquals({
+				class: undefined,
+				className: false
+			})
+			o(m('a', {
+				class: true
+			}).attrs).deepEquals({
+				class: undefined,
+				className: true
+			})
+			console.log(m('a.x', {
+				class: null
+			}).attrs, {
+				class: undefined,
+				className: "x null"
+			})
+			o(m('a.x', {
+				class: null
+			}).attrs).deepEquals({
+				class: undefined,
+				className: "x null"
+			})
+			o(m('a.x', {
+				class: undefined
+			}).attrs).deepEquals({
+				class: undefined,
+				className: "x"
+			})
+			o(m('a.x', {
+				class: false
+			}).attrs).deepEquals({
+				class: undefined,
+				className: "x false"
+			})
+			o(m('a.x', {
+				class: true
+			}).attrs).deepEquals({
+				class: undefined,
+				className: "x true"
+			})
+			o(m('a', {
+				className: null
+			}).attrs).deepEquals({
+				className: null
+			})
+			o(m('a', {
+				className: undefined
+			}).attrs).deepEquals({
+				className: undefined
+			})
+			o(m('a', {
+				className: false
+			}).attrs).deepEquals({
+				className: false
+			})
+			o(m('a', {
+				className: true
+			}).attrs).deepEquals({
+				className: true
+			})
+			o(m('a.x', {
+				className: null
+			}).attrs).deepEquals({
+				className: "x"
+			})
+			o(m('a.x', {
+				className: undefined
+			}).attrs).deepEquals({
+				className: "x"
+			})
+			o(m('a.x', {
+				className: false
+			}).attrs).deepEquals({
+				className: "x"
+			})
+			o(m('a.x', {
+				className: true
+			}).attrs).deepEquals({
+				className: "x true"
+			})
+		})
 		o("handles class in selector", function() {
 			var vnode = m(".a")