setAttr/removeAttr: remove key === "is", fixes MithrilJS#2799

This allows the "is" attribute to be set or removed like any other attribute.

Author: kfule

render/render.js

@@ -643,7 +643,7 @@ module.exports = function() {
 		}
 	}
 	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 === "key" || 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)
@@ -676,7 +676,7 @@ module.exports = function() {
 		}
 	}
 	function removeAttr(vnode, key, old, ns) {
-		if (key === "key" || key === "is" || old == null || isLifecycleMethod(key)) return
+		if (key === "key" || old == null || isLifecycleMethod(key)) return
 		if (key[0] === "o" && key[1] === "n") updateEvent(vnode, key, undefined)
 		else if (key === "style") updateStyle(vnode.dom, old, null)
 		else if (

render/tests/test-attributes.js

@@ -80,8 +80,8 @@ o.spec("attributes", function() {
 			o(spies[0].callCount).equals(0)
 			o(spies[2].callCount).equals(0)
 			o(spies[3].calls).deepEquals([{this: spies[3].elem, args: ["custom", "x"]}])
-			o(spies[4].calls).deepEquals([{this: spies[4].elem, args: ["custom", "x"]}])
-			o(spies[5].calls).deepEquals([{this: spies[5].elem, args: ["custom", "x"]}])
+			o(spies[4].calls).deepEquals([{this: spies[4].elem, args: ["is", "something-special"]}, {this: spies[4].elem, args: ["custom", "x"]}])
+			o(spies[5].calls).deepEquals([{this: spies[5].elem, args: ["is", "something-special"]}, {this: spies[5].elem, args: ["custom", "x"]}])
 		})
 
 		o("when vnode is customElement with property, custom setAttribute not called", function(){
@@ -124,8 +124,8 @@ o.spec("attributes", function() {
 			o(spies[1].callCount).equals(0)
 			o(spies[2].callCount).equals(0)
 			o(spies[3].callCount).equals(0)
-			o(spies[4].callCount).equals(0)
-			o(spies[5].callCount).equals(0)
+			o(spies[4].callCount).equals(1) // setAttribute("is", "something-special") is called
+			o(spies[5].callCount).equals(1) // setAttribute("is", "something-special") is called
 			o(getters[0].callCount).equals(0)
 			o(getters[1].callCount).equals(0)
 			o(getters[2].callCount).equals(0)