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         hasSuggestions: true,
  21         type: "suggestion",
  22
  23         docs: {
  24             description: "Disallow empty block statements",
  25             recommended: true,
  26             url: "https://eslint.org/docs/latest/rules/no-empty"
  27         },
  28
  29         schema: [
  30             {
  31                 type: "object",
  32                 properties: {
  33                     allowEmptyCatch: {
  34                         type: "boolean",
  35                         default: false
  36                     }
  37                 },
  38                 additionalProperties: false
  39             }
  40         ],
  41
  42         messages: {
  43             unexpected: "Empty {{type}} statement.",
  44             suggestComment: "Add comment inside empty {{type}} statement."
  45         }
  46     },
  47
  48     create(context) {
  49         const options = context.options[0] || {},
  50             allowEmptyCatch = options.allowEmptyCatch || false;
  51
  52         const sourceCode = context.sourceCode;
  53
  54         return {
  55             BlockStatement(node) {
  56
  57                 // if the body is not empty, we can just return immediately
  58                 if (node.body.length !== 0) {
  59                     return;
  60                 }
  61
  62                 // a function is generally allowed to be empty
  63                 if (astUtils.isFunction(node.parent)) {
  64                     return;
  65                 }
  66
  67                 if (allowEmptyCatch && node.parent.type === "CatchClause") {
  68                     return;
  69                 }
  70
  71                 // any other block is only allowed to be empty, if it contains a comment
  72                 if (sourceCode.getCommentsInside(node).length > 0) {
  73                     return;
  74                 }
  75
  76                 context.report({
  77                     node,
  78                     messageId: "unexpected",
  79                     data: { type: "block" },
  80                     suggest: [
  81                         {
  82                             messageId: "suggestComment",
  83                             data: { type: "block" },
  84                             fix(fixer) {
  85                                 const range = [node.range[0] + 1, node.range[1] - 1];
  86
  87                                 return fixer.replaceTextRange(range, " /* empty */ ");
  88                             }
  89                         }
  90                     ]
  91                 });
  92             },
  93
  94             SwitchStatement(node) {
  95
  96                 if (typeof node.cases === "undefined" || node.cases.length === 0) {
  97                     context.report({ node, messageId: "unexpected", data: { type: "switch" } });
  98                 }
  99             }
 100         };
 101
 102     }
 103 };