eslint/lib/rules/no-sparse-arrays.js

   1 /**
   2  * @fileoverview Disallow sparse arrays
   3  * @author Nicholas C. Zakas
   4  */
   5 "use strict";
   6
   7 //------------------------------------------------------------------------------
   8 // Rule Definition
   9 //------------------------------------------------------------------------------
  10
  11 module.exports = {
  12     meta: {
  13         type: "problem",
  14
  15         docs: {
  16             description: "disallow sparse arrays",
  17             category: "Possible Errors",
  18             recommended: true,
  19             url: "https://eslint.org/docs/rules/no-sparse-arrays"
  20         },
  21
  22         schema: [],
  23
  24         messages: {
  25             unexpectedSparseArray: "Unexpected comma in middle of array."
  26         }
  27     },
  28
  29     create(context) {
  30
  31
  32         //--------------------------------------------------------------------------
  33         // Public
  34         //--------------------------------------------------------------------------
  35
  36         return {
  37
  38             ArrayExpression(node) {
  39
  40                 const emptySpot = node.elements.indexOf(null) > -1;
  41
  42                 if (emptySpot) {
  43                     context.report({ node, messageId: "unexpectedSparseArray" });
  44                 }
  45             }
  46
  47         };
  48
  49     }
  50 };