Merge pull request #488 from sveltejs/component-binding-blowback

prevent binding blowback on initial render

src/generators/dom/visitors/Component/Binding.js

@@ -51,7 +51,7 @@ export default function visitBinding ( generator, block, state, node, attribute,
 				${updating} = true;
 				${setter}
 				${updating} = false;
-			});
+			}, { init: ${generator.helper( 'differs' )}( ${local.name}.get( '${attribute.name}' ), ${snippet} ) });
 		});
 	` );
 

test/runtime/samples/component-binding-blowback/Widget.html

@@ -0,0 +1 @@
+<p>does nothing</p>

test/runtime/samples/component-binding-blowback/_config.js

@@ -0,0 +1,14 @@
+export default {
+	test ( assert, component ) {
+		let count = 0;
+
+		component.observe( 'bar', () => {
+			count += 1;
+		});
+
+		component.set({ x: true });
+		assert.equal( count, 1 );
+
+		component.destroy();
+	}
+};

test/runtime/samples/component-binding-blowback/main.html

@@ -0,0 +1,22 @@
+{{#if x}}
+	<Widget bind:foo='bar.baz'/>
+{{/if}}
+
+<script>
+	import Widget from './Widget.html';
+
+	export default {
+		data: function () {
+			return {
+				x: false,
+				bar: {
+					baz: 42
+				}
+			};
+		},
+
+		components: {
+			Widget
+		}
+	};
+</script>

test/runtime/samples/component-binding-each/_config.js

@@ -16,7 +16,7 @@ export default {
 			<input><input><input>
 			<p>blah, bar, baz</p>
 		` );
-		
+
 		component.destroy();
 	}
 };