no-anonymous-default-export.js

/**
 * @fileoverview Rule to disallow anonymous default exports.
 * @author Duncan Beevers
 */

import docsUrl from '../docsUrl'
import has from 'has'

const defs = {
  ArrayExpression: {
    option: 'allowArray',
    description: 'If `false`, will report default export of an array',
    message: 'Assign array to a variable before exporting as module default',
  },
  ArrowFunctionExpression: {
    option: 'allowArrowFunction',
    description: 'If `false`, will report default export of an arrow function',
    message: 'Assign arrow function to a variable before exporting as module default',
  },
  CallExpression: {
    option: 'allowCallExpression',
    description: 'If `false`, will report default export of a function call',
    message: 'Assign call result to a variable before exporting as module default',
    default: true,
  },
  ClassDeclaration: {
    option: 'allowAnonymousClass',
    description: 'If `false`, will report default export of an anonymous class',
    message: 'Unexpected default export of anonymous class',
    forbid: (node) => !node.declaration.id,
  },
  FunctionDeclaration: {
    option: 'allowAnonymousFunction',
    description: 'If `false`, will report default export of an anonymous function',
    message: 'Unexpected default export of anonymous function',
    forbid: (node) => !node.declaration.id,
  },
  Literal: {
    option: 'allowLiteral',
    description: 'If `false`, will report default export of a literal',
    message: 'Assign literal to a variable before exporting as module default',
  },
  ObjectExpression: {
    option: 'allowObject',
    description: 'If `false`, will report default export of an object expression',
    message: 'Assign object to a variable before exporting as module default',
  },
  TemplateLiteral: {
    option: 'allowLiteral',
    description: 'If `false`, will report default export of a literal',
    message: 'Assign literal to a variable before exporting as module default',
  },
}

const schemaProperties = Object.keys(defs)
  .map((key) => defs[key])
  .reduce((acc, def) => {
    acc[def.option] = {
      description: def.description,
      type: 'boolean',
    }

    return acc
  }, {})

const defaults = Object.keys(defs)
  .map((key) => defs[key])
  .reduce((acc, def) => {
    acc[def.option] = has(def, 'default') ? def.default : false
    return acc
  }, {})

module.exports = {
  meta: {
    docs: {
      url: docsUrl('no-anonymous-default-export'),
    },

    schema: [
      {
        type: 'object',
        properties: schemaProperties,
        'additionalProperties': false,
      },
    ],
  },

  create: function (context) {
    const options = Object.assign({}, defaults, context.options[0])

    return {
      'ExportDefaultDeclaration': (node) => {
        const def = defs[node.declaration.type]

        // Recognized node type and allowed by configuration,
        //   and has no forbid check, or forbid check return value is truthy
        if (def && !options[def.option] && (!def.forbid || def.forbid(node))) {
          context.report({ node, message: def.message })
        }
      },
    }
  },
}