eslint/lib/rules/no-empty.js

   1 /**
   2  * @fileoverview Rule to flag use of an empty block statement
   3  * @author Nicholas C. Zakas
   4  */
   5 "use strict";
   6
   7 //------------------------------------------------------------------------------
   8 // Requirements
   9 //------------------------------------------------------------------------------
  10
  11 const astUtils = require("./utils/ast-utils");
  12
  13 //------------------------------------------------------------------------------
  14 // Rule Definition
  15 //------------------------------------------------------------------------------
  16
  17 /** @type {import('../shared/types').Rule} */
  18 module.exports = {
  19     meta: {
  20         type: "suggestion",
  21
  22         docs: {
  23             description: "Disallow empty block statements",
  24             recommended: true,
  25             url: "https://eslint.org/docs/rules/no-empty"
  26         },
  27
  28         schema: [
  29             {
  30                 type: "object",
  31                 properties: {
  32                     allowEmptyCatch: {
  33                         type: "boolean",
  34                         default: false
  35                     }
  36                 },
  37                 additionalProperties: false
  38             }
  39         ],
  40
  41         messages: {
  42             unexpected: "Empty {{type}} statement."
  43         }
  44     },
  45
  46     create(context) {
  47         const options = context.options[0] || {},
  48             allowEmptyCatch = options.allowEmptyCatch || false;
  49
  50         const sourceCode = context.getSourceCode();
  51
  52         return {
  53             BlockStatement(node) {
  54
  55                 // if the body is not empty, we can just return immediately
  56                 if (node.body.length !== 0) {
  57                     return;
  58                 }
  59
  60                 // a function is generally allowed to be empty
  61                 if (astUtils.isFunction(node.parent)) {
  62                     return;
  63                 }
  64
  65                 if (allowEmptyCatch && node.parent.type === "CatchClause") {
  66                     return;
  67                 }
  68
  69                 // any other block is only allowed to be empty, if it contains a comment
  70                 if (sourceCode.getCommentsInside(node).length > 0) {
  71                     return;
  72                 }
  73
  74                 context.report({ node, messageId: "unexpected", data: { type: "block" } });
  75             },
  76
  77             SwitchStatement(node) {
  78
  79                 if (typeof node.cases === "undefined" || node.cases.length === 0) {
  80                     context.report({ node, messageId: "unexpected", data: { type: "switch" } });
  81                 }
  82             }
  83         };
  84
  85     }
  86 };