Merge pull request #170 from sveltejs/gh-162

Allow event handlers to call methods of `event` and `this`

src/generate/visitors/attributes/addElementAttributes.js

@@ -1,6 +1,7 @@
 import attributeLookup from './lookup.js';
 import createBinding from './binding/index.js';
 import deindent from '../../../utils/deindent.js';
+import flattenReference from '../../../utils/flattenReference.js';
 
 export default function addElementAttributes ( generator, node, local ) {
 	node.attributes.forEach( attribute => {
@@ -114,7 +115,12 @@ export default function addElementAttributes ( generator, node, local ) {
 		else if ( attribute.type === 'EventHandler' ) {
 			// TODO verify that it's a valid callee (i.e. built-in or declared method)
 			generator.addSourcemapLocations( attribute.expression );
-			generator.code.prependRight( attribute.expression.start, 'component.' );
+
+			const flattened = flattenReference( attribute.expression.callee );
+			if ( flattened.name !== 'event' && flattened.name !== 'this' ) {
+				// allow event.stopPropagation(), this.select() etc
+				generator.code.prependRight( attribute.expression.start, 'component.' );
+			}
 
 			const usedContexts = new Set();
 			attribute.expression.arguments.forEach( arg => {

src/utils/flattenReference.js

@@ -7,10 +7,10 @@ export default function flatten ( node ) {
 		node = node.object;
 	}
 
-	if ( node.type !== 'Identifier' ) return null;
+	const name = node.type === 'Identifier' ? node.name : node.type === 'ThisExpression' ? 'this' : null;
 
-	const name = node.name;
+	if ( !name ) return null;
-	parts.unshift( name );
 
+	parts.unshift( name );
 	return { name, keypath: parts.join( '.' ) };
 }

test/generator/event-handler-event-methods/_config.js

@@ -0,0 +1,12 @@
+export default {
+	test ( assert, component, target, window ) {
+		const allow = target.querySelector( '.allow-propagation' );
+		const stop = target.querySelector( '.stop-propagation' );
+
+		allow.dispatchEvent( new window.MouseEvent( 'click', { bubbles: true }) );
+		stop.dispatchEvent( new window.MouseEvent( 'click', { bubbles: true }) );
+
+		assert.equal( component.get( 'foo' ), true );
+		assert.equal( component.get( 'bar' ), false );
+	}
+};

test/generator/event-handler-event-methods/main.html

@@ -0,0 +1,18 @@
+<div on:click='set({ foo: true })'>
+	<button class='allow-propagation'>click me</button>
+</div>
+
+<div on:click='set({ bar: true })'>
+	<button class='stop-propagation' on:click='event.stopPropagation()'>click me</button>
+</div>
+
+<script>
+	export default {
+		data () {
+			return {
+				foo: false,
+				bar: false
+			};
+		}
+	};
+</script>

test/generator/event-handler-this-methods/_config.js

@@ -0,0 +1,16 @@
+export default {
+	test ( assert, component, target, window ) {
+		// Click events don't focus elements in JSDOM – obviously they would
+		// in real browsers. More realistically, you'd use this for e.g.
+		// this.select(), but that's harder to test than this.focus()
+
+		const wont = target.querySelector( '.wont-focus' );
+		const will = target.querySelector( '.will-focus' );
+
+		wont.dispatchEvent( new window.MouseEvent( 'click' ) );
+		assert.equal( window.document.activeElement, window.document.body );
+
+		will.dispatchEvent( new window.MouseEvent( 'click' ) );
+		assert.equal( window.document.activeElement, will );
+	}
+};

test/generator/event-handler-this-methods/main.html

@@ -0,0 +1,2 @@
+<input class='wont-focus'>
+<input class='will-focus' on:click='this.focus()'>