build_element_attribute_update() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js lines 646–699

function build_element_attribute_update(element, node_id, name, value, attributes) {
	if (name === 'muted') {
		// Special case for Firefox who needs it set as a property in order to work
		return b.assignment('=', b.member(node_id, b.id('muted')), value);
	}

	if (name === 'value') {
		return b.call('$.set_value', node_id, value);
	}

	if (name === 'checked') {
		return b.call('$.set_checked', node_id, value);
	}

	if (name === 'selected') {
		return b.call('$.set_selected', node_id, value);
	}

	if (
		// If we would just set the defaultValue property, it would override the value property,
		// because it is set in the template which implicitly means it's also setting the default value,
		// and if one updates the default value while the input is pristine it will also update the
		// current value, which is not what we want, which is why we need to do some extra work.
		name === 'defaultValue' &&
		(attributes.some(
			(attr) => attr.type === 'Attribute' && attr.name === 'value' && is_text_attribute(attr)
		) ||
			(element.name === 'textarea' && element.fragment.nodes.length > 0))
	) {
		return b.call('$.set_default_value', node_id, value);
	}

	if (
		// See defaultValue comment
		name === 'defaultChecked' &&
		attributes.some(
			(attr) => attr.type === 'Attribute' && attr.name === 'checked' && attr.value === true
		)
	) {
		return b.call('$.set_default_checked', node_id, value);
	}

	if (is_dom_property(name)) {
		return b.assignment('=', b.member(node_id, name), value);
	}

	return b.call(
		name.startsWith('xlink') ? '$.set_xlink_attribute' : '$.set_attribute',
		node_id,
		b.literal(name),
		value,
		is_ignored(element, 'hydration_attribute_changed') && b.true
	);
}