eslint-plugin-lit/lib/rules/prefer-nothing.js

lit-html support for ESLint

/**
 * @fileoverview Enforces use of `nothing` constant over empty templates
 * @author James Garbutt <https://github.com/43081j>
 */
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
export const rule = {
    meta: {
        docs: {
            description: 'Enforces use of `nothing` constant over empty templates',
            recommended: false,
            url: 'https://github.com/43081j/eslint-plugin-lit/blob/master/docs/rules/prefer-nothing.md'
        },
        hasSuggestions: true,
        schema: [],
        messages: {
            preferNothing: '`nothing` is preferred over empty templates when you want to render' +
                ' nothing',
            useNothing: 'Replace empty template with `nothing` constant'
        }
    },
    create(context) {
        return {
            TaggedTemplateExpression: (node) => {
                if (node.type === 'TaggedTemplateExpression' &&
                    node.tag.type === 'Identifier' &&
                    node.tag.name === 'html') {
                    if (node.quasi.expressions.length === 0 &&
                        node.quasi.quasis.length === 1 &&
                        node.quasi.quasis[0].value.raw === '') {
                        context.report({
                            node,
                            messageId: 'preferNothing',
                            suggest: [
                                {
                                    messageId: 'useNothing',
                                    fix: (fixer) => {
                                        return fixer.replaceText(node, 'nothing');
                                    }
                                }
                            ]
                        });
                    }
                }
            }
        };
    }
};