visit_event_attribute() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/events.js lines 13–63

export function visit_event_attribute(node, context) {
	let capture = false;

	let event_name = node.name.slice(2);
	if (is_capture_event(event_name)) {
		event_name = event_name.slice(0, -7);
		capture = true;
	}

	// we still need to support the weird `onclick="{() => {...}}" form
	const tag = Array.isArray(node.value)
		? /** @type {AST.ExpressionTag} */ (node.value[0])
		: /** @type {AST.ExpressionTag} */ (node.value);

	let handler = build_event_handler(tag.expression, tag.metadata.expression, context);

	if (node.metadata.delegated) {
		if (!context.state.events.has(event_name)) {
			context.state.events.add(event_name);
		}

		context.state.init.push(
			b.stmt(
				b.assignment(
					'=',
					b.member(context.state.node, b.id('__' + event_name, node.name_loc)),
					handler
				)
			)
		);
	} else {
		const statement = b.stmt(
			build_event(
				event_name,
				context.state.node,
				handler,
				capture,
				is_passive_event(event_name) ? true : undefined
			)
		);

		const type = /** @type {AST.SvelteNode} */ (context.path.at(-1)).type;

		if (type === 'SvelteDocument' || type === 'SvelteWindow' || type === 'SvelteBody') {
			// These nodes are above the component tree, and its events should run parent first
			context.state.init.push(statement);
		} else {
			context.state.after_update.push(statement);
		}
	}
}