no-mutable-exports.js

import docsUrl from '../docsUrl'

module.exports = {
  meta: {
    type: 'suggestion',
    docs: {
      url: docsUrl('no-mutable-exports'),
    },
  },

  create: function (context) {
    function checkDeclaration(node) {
      const {kind} = node
      if (kind === 'var' || kind === 'let') {
        context.report(node, `Exporting mutable '${kind}' binding, use 'const' instead.`)
      }
    }

    function checkDeclarationsInScope({variables}, name) {
      for (let variable of variables) {
        if (variable.name === name) {
          for (let def of variable.defs) {
            if (def.type === 'Variable' && def.parent) {
              checkDeclaration(def.parent)
            }
          }
        }
      }
    }

    function handleExportDefault(node) {
      const scope = context.getScope()

      if (node.declaration.name) {
        checkDeclarationsInScope(scope, node.declaration.name)
      }
    }

    function handleExportNamed(node) {
      const scope = context.getScope()

      if (node.declaration)  {
        checkDeclaration(node.declaration)
      } else if (!node.source) {
        for (let specifier of node.specifiers) {
          checkDeclarationsInScope(scope, specifier.local.name)
        }
      }
    }

    return {
      'ExportDefaultDeclaration': handleExportDefault,
      'ExportNamedDeclaration': handleExportNamed,
    }
  },
}