eslint/lib/rules/global-require.js

   1 /**
   2  * @fileoverview Rule for disallowing require() outside of the top-level module context
   3  * @author Jamund Ferguson
   4  */
   5
   6 "use strict";
   7
   8 const ACCEPTABLE_PARENTS = [
   9     "AssignmentExpression",
  10     "VariableDeclarator",
  11     "MemberExpression",
  12     "ExpressionStatement",
  13     "CallExpression",
  14     "ConditionalExpression",
  15     "Program",
  16     "VariableDeclaration"
  17 ];
  18
  19 /**
  20  * Finds the eslint-scope reference in the given scope.
  21  * @param {Object} scope The scope to search.
  22  * @param {ASTNode} node The identifier node.
  23  * @returns {Reference|null} Returns the found reference or null if none were found.
  24  */
  25 function findReference(scope, node) {
  26     const references = scope.references.filter(reference => reference.identifier.range[0] === node.range[0] &&
  27             reference.identifier.range[1] === node.range[1]);
  28
  29     /* istanbul ignore else: correctly returns null */
  30     if (references.length === 1) {
  31         return references[0];
  32     }
  33     return null;
  34
  35 }
  36
  37 /**
  38  * Checks if the given identifier node is shadowed in the given scope.
  39  * @param {Object} scope The current scope.
  40  * @param {ASTNode} node The identifier node to check.
  41  * @returns {boolean} Whether or not the name is shadowed.
  42  */
  43 function isShadowed(scope, node) {
  44     const reference = findReference(scope, node);
  45
  46     return reference && reference.resolved && reference.resolved.defs.length > 0;
  47 }
  48
  49 module.exports = {
  50     meta: {
  51         type: "suggestion",
  52
  53         docs: {
  54             description: "require `require()` calls to be placed at top-level module scope",
  55             category: "Node.js and CommonJS",
  56             recommended: false,
  57             url: "https://eslint.org/docs/rules/global-require"
  58         },
  59
  60         schema: [],
  61         messages: {
  62             unexpected: "Unexpected require()."
  63         }
  64     },
  65
  66     create(context) {
  67         return {
  68             CallExpression(node) {
  69                 const currentScope = context.getScope();
  70
  71                 if (node.callee.name === "require" && !isShadowed(currentScope, node.callee)) {
  72                     const isGoodRequire = context.getAncestors().every(parent => ACCEPTABLE_PARENTS.indexOf(parent.type) > -1);
  73
  74                     if (!isGoodRequire) {
  75                         context.report({ node, messageId: "unexpected" });
  76                     }
  77                 }
  78             }
  79         };
  80     }
  81 };