validate_no_const_assignment() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/utils.js lines 84–123

export function validate_no_const_assignment(node, argument, scope, is_binding) {
	if (argument.type === 'ArrayPattern') {
		for (const element of argument.elements) {
			if (element) {
				validate_no_const_assignment(node, element, scope, is_binding);
			}
		}
	} else if (argument.type === 'ObjectPattern') {
		for (const element of argument.properties) {
			if (element.type === 'Property') {
				validate_no_const_assignment(node, element.value, scope, is_binding);
			}
		}
	} else if (argument.type === 'Identifier') {
		const binding = scope.get(argument.name);
		if (
			binding?.declaration_kind === 'import' ||
			(binding?.declaration_kind === 'const' && binding.kind !== 'each')
		) {
			// e.invalid_const_assignment(
			// 	node,
			// 	is_binding,
			// 	// This takes advantage of the fact that we don't assign initial for let directives and then/catch variables.
			// 	// If we start doing that, we need another property on the binding to differentiate, or give up on the more precise error message.
			// 	binding.kind !== 'state' &&
			// 		binding.kind !== 'raw_state' &&
			// 		(binding.kind !== 'normal' || !binding.initial)
			// );

			// TODO have a more specific error message for assignments to things like `{:then foo}`
			const thing = binding.declaration_kind === 'import' ? 'import' : 'constant';

			if (is_binding) {
				e.constant_binding(node, thing);
			} else {
				e.constant_assignment(node, thing);
			}
		}
	}
}