react-scripts/node_modules/eslint-plugin-react/lib/rules/require-render-return.js

Configuration and scripts for Create React App.

/**
 * @fileoverview Enforce ES5 or ES6 class for returning value in render function.
 * @author Mark Orel
 */
'use strict';

var Components = require('../util/Components');

// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------

module.exports = Components.detect(function(context, components, utils) {

  /**
   * Mark a return statement as present
   * @param {ASTNode} node The AST node being checked.
   */
  function markReturnStatementPresent(node) {
    components.set(node, {
      hasReturnStatement: true
    });
  }

  /**
   * Get properties for a given AST node
   * @param {ASTNode} node The AST node being checked.
   * @returns {Array} Properties array.
   */
  function getComponentProperties(node) {
    switch (node.type) {
      case 'ClassDeclaration':
        return node.body.body;
      case 'ObjectExpression':
        return node.properties;
      default:
        return [];
    }
  }

  /**
   * Get properties name
   * @param {Object} node - Property.
   * @returns {String} Property name.
   */
  function getPropertyName(node) {
    // Special case for class properties
    // (babel-eslint does not expose property name so we have to rely on tokens)
    if (node.type === 'ClassProperty') {
      var tokens = context.getFirstTokens(node, 2);
      return tokens[1] && tokens[1].type === 'Identifier' ? tokens[1].value : tokens[0].value;
    } else if (['MethodDefinition', 'Property'].indexOf(node.type) !== -1) {
      return node.key.name;
    }
    return '';
  }

  /**
   * Check if a given AST node has a render method
   * @param {ASTNode} node The AST node being checked.
   * @returns {Boolean} True if there is a render method, false if not
   */
  function hasRenderMethod(node) {
    var properties = getComponentProperties(node);
    for (var i = 0, j = properties.length; i < j; i++) {
      if (getPropertyName(properties[i]) !== 'render') {
        continue;
      }
      return /FunctionExpression$/.test(properties[i].value.type);
    }
    return false;
  }

  return {
    ReturnStatement: function(node) {
      var ancestors = context.getAncestors(node).reverse();
      var depth = 0;
      for (var i = 0, j = ancestors.length; i < j; i++) {
        if (/Function(Expression|Declaration)$/.test(ancestors[i].type)) {
          depth++;
        }
        if (
          !/(MethodDefinition|(Class)?Property)$/.test(ancestors[i].type) ||
          getPropertyName(ancestors[i]) !== 'render' ||
          depth > 1
        ) {
          continue;
        }
        markReturnStatementPresent(node);
      }
    },

    ArrowFunctionExpression: function(node) {
      if (node.expression === false || getPropertyName(node.parent) !== 'render') {
        return;
      }
      markReturnStatementPresent(node);
    },

    'Program:exit': function() {
      var list = components.list();
      for (var component in list) {
        if (
          !list.hasOwnProperty(component) ||
          !hasRenderMethod(list[component].node) ||
          list[component].hasReturnStatement ||
          (!utils.isES5Component(list[component].node) && !utils.isES6Component(list[component].node))
        ) {
          continue;
        }
        context.report({
          node: list[component].node,
          message: 'Your render method should have return statement'
        });
      }
    }
  };
});

module.exports.schema = [{}];