VariableDeclaration() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/3-transform/client/visitors/VariableDeclaration.js lines 16–380

export function VariableDeclaration(node, context) {
	/** @type {VariableDeclarator[]} */
	const declarations = [];

	if (context.state.analysis.runes) {
		for (const declarator of node.declarations) {
			const init = /** @type {Expression} */ (declarator.init);
			const rune = get_rune(init, context.state.scope);

			if (
				!rune ||
				rune === '$effect.tracking' ||
				rune === '$effect.root' ||
				rune === '$inspect' ||
				rune === '$inspect.trace' ||
				rune === '$state.snapshot' ||
				rune === '$host'
			) {
				declarations.push(/** @type {VariableDeclarator} */ (context.visit(declarator)));
				continue;
			}

			if (rune === '$props.id') {
				// skip
				continue;
			}

			if (rune === '$props') {
				/** @type {string[]} */
				const seen = ['$$slots', '$$events', '$$legacy'];

				if (context.state.analysis.custom_element) {
					seen.push('$$host');
				}

				if (declarator.id.type === 'Identifier') {
					/** @type {Expression[]} */
					const args = [b.id('$$props'), b.array(seen.map((name) => b.literal(name)))];

					if (dev) {
						// include rest name, so we can provide informative error messages
						args.push(b.literal(declarator.id.name));
					}

					declarations.push(b.declarator(declarator.id, b.call('$.rest_props', ...args)));
				} else {
					assert.equal(declarator.id.type, 'ObjectPattern');

					for (const property of declarator.id.properties) {
						if (property.type === 'Property') {
							const key = /** @type {Identifier | Literal} */ (property.key);
							const name = key.type === 'Identifier' ? key.name : /** @type {string} */ (key.value);

							seen.push(name);

							let id =
								property.value.type === 'AssignmentPattern' ? property.value.left : property.value;
							assert.equal(id.type, 'Identifier');
							const binding = /** @type {Binding} */ (context.state.scope.get(id.name));
							let initial =
								binding.initial && /** @type {Expression} */ (context.visit(binding.initial));
							// We're adding proxy here on demand and not within the prop runtime function so that
							// people not using proxied state anywhere in their code don't have to pay the additional bundle size cost
							if (
								initial &&
								binding.kind === 'bindable_prop' &&
								should_proxy(initial, context.state.scope)
							) {
								initial = b.call('$.proxy', initial);

								if (dev) {
									initial = b.call('$.tag_proxy', initial, b.literal(id.name));
								}
							}

							if (is_prop_source(binding, context.state)) {
								declarations.push(
									b.declarator(id, get_prop_source(binding, context.state, name, initial))
								);
							}
						} else {