refactor: tidy up compile/nodes

src/compiler/compile/nodes/Binding.ts

@@ -101,12 +101,11 @@ export default class Binding extends Node {
 	validate_binding_rest_properties(scope: TemplateScope) {
 		this.expression.references.forEach(name => {
 			const each_block = scope.get_owner(name);
-			if (each_block && each_block.type === 'EachBlock') {
+			if (!each_block || each_block.type !== 'EachBlock') return;
 			const rest_node = each_block.context_rest_properties.get(name);
 			if (rest_node) {
 				this.component.warn(rest_node as any, compiler_warnings.invalid_rest_eachblock_binding(name));
 			}
-			}
 		});
 	}
 }

src/compiler/compile/nodes/ConstTag.ts

@@ -66,7 +66,7 @@ export default class ConstTag extends Node {
 		this.expression = new Expression(this.component, this, this.scope, this.node.expression.right);
 		this.contexts.forEach(context => {
 			const owner = this.scope.get_owner(context.key.name);
-			if (owner && owner.type === 'ConstTag' && owner.parent === this.parent) {
+			if (owner?.type === 'ConstTag' && owner?.parent === this.parent) {
 				this.component.error(this.node, compiler_errors.invalid_const_declaration(context.key.name));
 			}
 			this.scope.add(context.key.name, this.expression.dependencies, this);

src/compiler/compile/nodes/DebugTag.ts

@@ -13,8 +13,6 @@ export default class DebugTag extends Node {
 	constructor(component: Component, parent: INode, scope: TemplateScope, info: TemplateNode) {
 		super(component, parent, scope, info);
 
-		this.expressions = info.identifiers.map((node: EsTreeNode) => {
-			return new Expression(component, parent, scope, node);
-		});
+		this.expressions = info.identifiers.map((node: EsTreeNode) => new Expression(component, parent, scope, node));
 	}
 }

src/compiler/compile/nodes/Element.ts

@@ -261,8 +261,7 @@ export default class Element extends Node {
 				}
 			}
 
-			if (this.name === 'textarea') {
-				if (info.children.length > 0) {
+			if (this.name === 'textarea' && info.children.length) {
 				const value_attribute = info.attributes.find(node => node.name === 'value');
 				if (value_attribute) {
 					component.error(value_attribute, compiler_errors.textarea_duplicate_value);
@@ -279,7 +278,6 @@ export default class Element extends Node {
 
 				info.children = [];
 			}
-			}
 
 			if (this.name === 'option') {
 				// Special case — treat these the same way:
@@ -688,20 +686,10 @@ export default class Element extends Node {
 
 		if (this.name === 'label') {
 			const has_input_child = (children: INode[]) => {
-				if (children.some(child => (child instanceof Element && (a11y_labelable.has(child.name) || child.name === 'slot')))) {
-					return true;
-				}
-
-				for (const child of children) {
-					if (!('children' in child) || child.children.length === 0) {
-						continue;
-					}
-					if (has_input_child(child.children)) {
-						return true;
-					}
-				}
-
-				return false;
+				return children.some(child => (child instanceof Element && (a11y_labelable.has(child.name) || child.name === 'slot'))) ||
+					children.some(child =>
+						('children' in child) && child.children.length && has_input_child(child.children)
+					);
 			};
 
 			if (!attribute_map.has('for') && !has_input_child(this.children)) {
@@ -714,11 +702,9 @@ export default class Element extends Node {
 				return;
 			}
 
-			let has_caption;
-			const track = this.children.find((i: Element) => i.name === 'track');
-			if (track) {
-				has_caption = track.attributes.find(a => a.name === 'kind' && a.get_static_value() === 'captions');
-			}
+			const has_caption = this.children
+				.find((i: Element) => i.name === 'track')
+				?.attributes.find(a => a.name === 'kind' && a.get_static_value() === 'captions');
 
 			if (!has_caption) {
 				component.warn(this, compiler_warnings.a11y_media_has_caption);
@@ -1011,7 +997,7 @@ export default class Element extends Node {
 			const attribute = this.attributes.find(a => a.name === attribute_name);
 			if (attribute && !attribute.is_true) {
 				attribute.chunks.forEach((chunk, index) => {
-					if (chunk.type === 'Text') {
+					if (chunk.type !== 'Text') return;
 					let data = chunk.data.replace(regex_any_repeated_whitespaces, ' ');
 					if (index === 0) {
 						data = data.trimLeft();
@@ -1019,7 +1005,6 @@ export default class Element extends Node {
 						data = data.trimRight();
 					}
 					chunk.data = data;
-					}
 				});
 			}
 		});

src/compiler/compile/nodes/EventHandler.ts

@@ -52,12 +52,8 @@ export default class EventHandler extends Node {
 	}
 
 	get reassigned(): boolean {
-		if (!this.expression) {
-			return false;
-		}
-		const node = this.expression.node;
-
-		if (regex_contains_term_function_expression.test(node.type)) {
+		if (!this.expression ||
+			regex_contains_term_function_expression.test(this.expression.node.type)) {
 			return false;
 		}
 

src/compiler/compile/nodes/Head.ts

@@ -24,7 +24,7 @@ export default class Head extends Node {
 			return (child.type !== 'Text' || regex_non_whitespace_character.test(child.data));
 		}));
 
-		if (this.children.length > 0) {
+		if (this.children.length) {
 			this.id = `svelte-${hash(this.component.source.slice(this.start, this.end))}`;
 		}
 	}

src/compiler/compile/nodes/InlineComponent.ts

@@ -172,9 +172,7 @@ function not_whitespace_text(node) {
 function get_namespace(parent: Node, explicit_namespace: string) {
 	const parent_element = parent.find_nearest(/^Element/);
 
-	if (!parent_element) {
-		return explicit_namespace;
-	}
-
-	return parent_element.namespace;
+	return !parent_element
+		? explicit_namespace
+		: parent_element.namespace;
 }

src/compiler/compile/nodes/SlotTemplate.ts

@@ -42,7 +42,10 @@ export default class SlotTemplate extends Node {
 					break;
 				}
 				case 'Attribute': {
-					if (node.name === 'slot') {
+					if (node.name !== 'slot') {
+						throw new Error(`Invalid attribute '${node.name}' in <svelte:fragment>`);
+					}
+
 					this.slot_attribute = new Attribute(component, this, scope, node);
 					if (!this.slot_attribute.is_static) {
 						return component.error(node, compiler_errors.invalid_slot_attribute);
@@ -54,8 +57,6 @@ export default class SlotTemplate extends Node {
 					this.slot_template_name = value as string;
 					break;
 				}
-					throw new Error(`Invalid attribute '${node.name}' in <svelte:fragment>`);
-				}
 				default:
 					throw new Error(`Not implemented: ${node.type}`);
 			}

src/compiler/compile/nodes/Text.ts

@@ -40,16 +40,15 @@ export default class Text extends Node {
 		if (parent_element.type === 'InlineComponent') return parent_element.children.length === 1 && this === parent_element.children[0];
 
 		// svg namespace exclusions
-		if (regex_ends_with_svg.test(parent_element.namespace)) {
-			if (this.prev && this.prev.type === 'Element' && this.prev.name === 'tspan') return false;
+		if (regex_ends_with_svg.test(parent_element.namespace) && this.prev?.type === 'Element' && this.prev?.name === 'tspan') {
+			return false;
 		}
 
 		return parent_element.namespace || elements_without_text.has(parent_element.name);
 	}
 
 	keep_space(): boolean {
-		if (this.component.component_options.preserveWhitespace) return true;
-		return this.within_pre();
+		return this.component.component_options.preserveWhitespace || this.within_pre();
 	}
 
 	within_pre(): boolean {

src/compiler/compile/nodes/Title.ts

@@ -14,7 +14,7 @@ export default class Title extends Node {
 		super(component, parent, scope, info);
 		this.children = map_children(component, parent, scope, info.children);
 
-		if (info.attributes.length > 0) {
+		if (info.attributes.length) {
 			component.error(info.attributes[0], compiler_errors.illegal_attribute_title);
 			return;
 		}

src/compiler/compile/nodes/Window.ts

@@ -47,11 +47,10 @@ export default class Window extends Node {
 								fuzzymatch(node.name, valid_bindings)
 					);
 
-					if (match) {
-						return component.error(node, compiler_errors.invalid_binding_on(node.name, '<svelte:window>', ` (did you mean '${match}'?)`));
-					} else {
-						return component.error(node, compiler_errors.invalid_binding_on(node.name, '<svelte:window>', ` — valid bindings are ${list(valid_bindings)}`));
-					}
+					return component.error(node, compiler_errors.invalid_binding_on(node.name, '<svelte:window>',
+						match
+							? ` (did you mean '${match}'?)`
+							: ` — valid bindings are ${list(valid_bindings)}`));
 				}
 
 				this.bindings.push(new Binding(component, this, scope, node));

src/compiler/compile/nodes/shared/AbstractBlock.ts

@@ -19,7 +19,7 @@ export default class AbstractBlock extends Node {
 
 		const child = this.children[0];
 
-		if (!child || (child.type === 'Text' && !regex_non_whitespace_characters.test(child.data))) {
+		if (child?.type === 'Text' && !regex_non_whitespace_characters.test(child.data)) {
 			this.component.warn(this, compiler_warnings.empty_block);
 		}
 	}

src/compiler/compile/nodes/shared/Context.ts

@@ -48,7 +48,7 @@ export function unpack_destructuring({
 		context_rest_properties.set((node.argument as Identifier).name, node);
 	} else if (node.type === 'ArrayPattern') {
 		node.elements.forEach((element, i) => {
-			if (element && element.type === 'RestElement') {
+			if (element?.type === 'RestElement') {
 				unpack_destructuring({
 					contexts,
 					node: element,
@@ -59,7 +59,7 @@ export function unpack_destructuring({
 					context_rest_properties
 				});
 				context_rest_properties.set((element.argument as Identifier).name, element);
-			} else if (element && element.type === 'AssignmentPattern') {
+			} else if (element?.type === 'AssignmentPattern') {
 				const n = contexts.length;
 				mark_referenced(element.right, scope, component);
 
@@ -195,12 +195,11 @@ function mark_referenced(
 ) {
 	walk(node, {
 		enter(node: any, parent: any) {
-			if (is_reference(node, parent)) {
+			if (!is_reference(node, parent)) return;
 			const { name } = flatten_reference(node);
 			if (!scope.is_let(name) && !scope.names.has(name)) {
 				component.add_reference(node, name);
 			}
 		}
-		}
 	});
 }

src/compiler/compile/nodes/shared/Expression.ts

@@ -133,8 +133,7 @@ export default class Expression {
 					}
 				}
 
-				if (names) {
-					names.forEach(name => {
+				names?.forEach(name => {
 					if (template_scope.names.has(name)) {
 						if (template_scope.is_const(name)) {
 							component.error(node, compiler_errors.invalid_const_update(name));
@@ -172,7 +171,6 @@ export default class Expression {
 						}
 					}
 				});
-				}
 			},
 
 			leave(node: Node) {
@@ -189,8 +187,8 @@ export default class Expression {
 
 	dynamic_dependencies() {
 		return Array.from(this.dependencies).filter(name => {
-			if (this.template_scope.is_let(name)) return true;
-			if (is_reserved_keyword(name)) return true;
+			if (this.template_scope.is_let(name) ||
+				is_reserved_keyword(name)) return true;
 
 			const variable = this.component.var_lookup.get(name);
 			return is_dynamic(variable);
@@ -428,11 +426,9 @@ export default class Expression {
 			}
 		});
 
-		if (declarations.length > 0) {
+		if (declarations.length) {
 			block.maintain_context = true;
-			declarations.forEach(declaration => {
-				block.chunks.init.push(declaration);
-			});
+			block.chunks.init.push(...declarations);
 		}
 
 		return (this.manipulated = node as Node);

src/compiler/compile/nodes/shared/Node.ts

@@ -36,11 +36,10 @@ export default class Node {
 	}
 
 	cannot_use_innerhtml() {
-		if (this.can_use_innerhtml !== false) {
+		if (this.can_use_innerhtml === false) return;
 		this.can_use_innerhtml = false;
 		if (this.parent) this.parent.cannot_use_innerhtml();
 	}
-	}
 
 	find_nearest(selector: RegExp) {
 		if (selector.test(this.type)) return this;

src/compiler/compile/nodes/shared/TemplateScope.ts

@@ -28,8 +28,7 @@ export default class TemplateScope {
 	}
 
 	child() {
-		const child = new TemplateScope(this);
-		return child;
+		return new TemplateScope(this);
 	}
 
 	is_top_level(name: string) {

src/compiler/compile/nodes/shared/get_const_tags.ts

@@ -65,7 +65,7 @@ function sort_consts_nodes(consts_nodes: ConstTag[], component: Component) {
 		return acc;
 	}, []));
 
-  if (cycle && cycle.length) {
+	if (cycle?.length) {
 		const nodeList = lookup.get(cycle[0]);
 		const node = nodeList[0];
 		component.error(node.node, compiler_errors.cyclical_const_tags(cycle));

src/compiler/compile/nodes/shared/is_contextual.ts

@@ -3,10 +3,11 @@ import TemplateScope from './TemplateScope';
 import { is_reserved_keyword } from '../../utils/reserved_keywords';
 
 export default function is_contextual(component: Component, scope: TemplateScope, name: string) {
-	if (is_reserved_keyword(name)) return true;
-
+	if (is_reserved_keyword(name) ||
 		// if it's a name below root scope, it's contextual
-	if (!scope.is_top_level(name)) return true;
+		!scope.is_top_level(name)
+	) return true;
+
 
 	const variable = component.var_lookup.get(name);