WIP - start seeing if we can unify init and update

src/compiler/compile/render_dom/Block.ts

@@ -287,11 +287,18 @@ export default class Block {
 			}`;
 		}
 
-		if (this.chunks.mount.length === 0) {
+		const needs_update_method = this.maintain_context || (this.chunks.update.length > 0 && this.has_update_method);
+
+		if (this.chunks.mount.length === 0 && this.chunks.update.length === 0) {
 			properties.mount = noop;
 		} else {
+			const dirty = this.renderer.context_overflow
+				? x`TODO` // this.renderer.dirty_expression
+				: this.parent ? x`-1` : x`[-1]`;
+
 			properties.mount = x`function #mount(#target, anchor) {
 				${this.chunks.mount}
+				${needs_update_method && b`this.p(#ctx, ${dirty});`}
 			}`;
 		}
 

src/compiler/compile/render_dom/wrappers/EachBlock.ts

@@ -203,7 +203,7 @@ export default class EachBlockWrapper extends Wrapper {
 
 		const snippet = this.node.expression.manipulate(block);
 
-		block.chunks.init.push(b`let ${this.vars.each_block_value} = ${snippet};`);
+		block.chunks.init.push(b`let ${this.vars.each_block_value} = [];`);
 
 		// TODO which is better — Object.create(array) or array.slice()?
 		renderer.blocks.push(b`
@@ -261,12 +261,12 @@ export default class EachBlockWrapper extends Wrapper {
 			block.chunks.init.push(b`let ${each_block_else} = null;`);
 
 			// TODO neaten this up... will end up with an empty line in the block
-			block.chunks.init.push(b`
+			// block.chunks.init.push(b`
-				if (!${this.vars.data_length}) {
+			// 	if (!${this.vars.data_length}) {
-					${each_block_else} = ${this.else.block.name}(#ctx);
+			// 		${each_block_else} = ${this.else.block.name}(#ctx);
-					${each_block_else}.c();
+			// 		${each_block_else}.c();
-				}
+			// 	}
-			`);
+			// `);
 
 			block.chunks.mount.push(b`
 				if (${each_block_else}) {
@@ -336,7 +336,6 @@ export default class EachBlockWrapper extends Wrapper {
 		const {
 			create_each_block,
 			iterations,
-			data_length,
 			view_length
 		} = this.vars;
 
@@ -360,12 +359,6 @@ export default class EachBlockWrapper extends Wrapper {
 
 		block.chunks.init.push(b`
 			const ${get_key} = #ctx => ${this.node.key.manipulate(block)};
-
-			for (let #i = 0; #i < ${data_length}; #i += 1) {
-				let child_ctx = ${this.vars.get_each_context}(#ctx, ${this.vars.each_block_value}, #i);
-				let key = ${get_key}(child_ctx);
-				${lookup}.set(key, ${iterations}[#i] = ${create_each_block}(key, child_ctx));
-			}
 		`);
 
 		block.chunks.create.push(b`
@@ -450,10 +443,6 @@ export default class EachBlockWrapper extends Wrapper {
 
 		block.chunks.init.push(b`
 			let ${iterations} = [];
-
-			for (let #i = 0; #i < ${data_length}; #i += 1) {
-				${iterations}[#i] = ${create_each_block}(${this.vars.get_each_context}(#ctx, ${this.vars.each_block_value}, #i));
-			}
 		`);
 
 		block.chunks.create.push(b`

src/compiler/compile/render_dom/wrappers/IfBlock.ts

@@ -500,7 +500,7 @@ export default class IfBlockWrapper extends Wrapper {
 
 	render_simple(
 		block: Block,
-		parent_node: Identifier,
+		_parent_node: Identifier,
 		_parent_nodes: Identifier,
 		dynamic,
 		{ name, anchor, if_exists_condition, has_transitions },
@@ -509,17 +509,7 @@ export default class IfBlockWrapper extends Wrapper {
 		const branch = this.branches[0];
 
 		if (branch.snippet) block.add_variable(branch.condition, branch.snippet);
-
+		block.add_variable(name);
-		block.chunks.init.push(b`
-			let ${name} = ${branch.condition} && ${branch.block.name}(#ctx);
-		`);
-
-		const initial_mount_node = parent_node || '#target';
-		const anchor_node = parent_node ? 'null' : 'anchor';
-
-		block.chunks.mount.push(
-			b`if (${name}) ${name}.m(${initial_mount_node}, ${anchor_node});`
-		);
 
 		if (branch.dependencies.length > 0) {
 			const update_mount_node = this.get_update_mount_node(anchor);

src/compiler/compile/render_dom/wrappers/Window.ts

@@ -139,13 +139,19 @@ export default class WindowWrapper extends Wrapper {
 
 		// special case... might need to abstract this out if we add more special cases
 		if (bindings.scrollX || bindings.scrollY) {
-			const condition = renderer.dirty([bindings.scrollX, bindings.scrollY].filter(Boolean));
-
 			const scrollX = bindings.scrollX ? renderer.reference(bindings.scrollX) : x`@_window.pageXOffset`;
 			const scrollY = bindings.scrollY ? renderer.reference(bindings.scrollY) : x`@_window.pageYOffset`;
 
+			let condition = x`
+				${renderer.dirty([bindings.scrollX, bindings.scrollY].filter(Boolean))} &&
+				!${scrolling}
+			`;
+
+			if (bindings.scrollX) condition = x`${condition} && !isNaN(${scrollX})`;
+			if (bindings.scrollY) condition = x`${condition} && !isNaN(${scrollY})`;
+
 			block.chunks.update.push(b`
-				if (${condition} && !${scrolling}) {
+				if (${condition}) {
 					${scrolling} = true;
 					@_clearTimeout(${scrolling_timeout});
 					@_scrollTo(${scrollX}, ${scrollY});

src/compiler/compile/render_dom/wrappers/shared/Tag.ts

@@ -31,12 +31,16 @@ export default class Tag extends Wrapper {
 		const dependencies = this.node.expression.dynamic_dependencies();
 		let snippet = this.node.expression.manipulate(block);
 
-		const value = this.node.should_cache && block.get_unique_name(`${this.var.name}_value`);
+		const value = block.get_unique_name(`${this.var.name}_value`);
 		const content = this.node.should_cache ? value : snippet;
 
 		snippet = x`${snippet} + ""`;
 
-		if (this.node.should_cache) block.add_variable(value, snippet); // TODO may need to coerce snippet to string
+		if (dependencies.length > 0) {
+			block.add_variable(value);
+		} else {
+			block.add_variable(value, snippet);
+		}
 
 		if (dependencies.length > 0) {
 			let condition = block.renderer.dirty(dependencies);
@@ -54,6 +58,8 @@ export default class Tag extends Wrapper {
 			block.chunks.update.push(b`if (${condition}) ${update(content as Node)}`);
 		}
 
-		return { init: content };
+		return {
+			init: value
+		};
 	}
 }

test/runtime/index.js

@@ -26,7 +26,7 @@ process.on('unhandledRejection', err => {
 	unhandled_rejection = err;
 });
 
-describe("runtime", () => {
+describe.only("runtime", () => {
 	before(() => {
 		svelte = loadSvelte(false);
 		svelte$ = loadSvelte(true);

test/runtime/samples/window-bind-scroll-update/_config.js

@@ -3,7 +3,7 @@ import { env, useFakeTimers } from "../../../helpers";
 let clock;
 
 export default {
-	before_test()  {
+	before_test() {
 		clock = useFakeTimers();
 
 		const window = env();