eslint/lib/rules/implicit-arrow-linebreak.js

   1 /**
   2  * @fileoverview enforce the location of arrow function bodies
   3  * @author Sharmila Jesupaul
   4  */
   5 "use strict";
   6
   7 const { isCommentToken, isNotOpeningParenToken } = require("./utils/ast-utils");
   8
   9 //------------------------------------------------------------------------------
  10 // Rule Definition
  11 //------------------------------------------------------------------------------
  12 /** @type {import('../shared/types').Rule} */
  13 module.exports = {
  14     meta: {
  15         type: "layout",
  16
  17         docs: {
  18             description: "Enforce the location of arrow function bodies",
  19             recommended: false,
  20             url: "https://eslint.org/docs/rules/implicit-arrow-linebreak"
  21         },
  22
  23         fixable: "whitespace",
  24
  25         schema: [
  26             {
  27                 enum: ["beside", "below"]
  28             }
  29         ],
  30         messages: {
  31             expected: "Expected a linebreak before this expression.",
  32             unexpected: "Expected no linebreak before this expression."
  33         }
  34     },
  35
  36     create(context) {
  37         const sourceCode = context.getSourceCode();
  38         const option = context.options[0] || "beside";
  39
  40         /**
  41          * Validates the location of an arrow function body
  42          * @param {ASTNode} node The arrow function body
  43          * @returns {void}
  44          */
  45         function validateExpression(node) {
  46             if (node.body.type === "BlockStatement") {
  47                 return;
  48             }
  49
  50             const arrowToken = sourceCode.getTokenBefore(node.body, isNotOpeningParenToken);
  51             const firstTokenOfBody = sourceCode.getTokenAfter(arrowToken);
  52
  53             if (arrowToken.loc.end.line === firstTokenOfBody.loc.start.line && option === "below") {
  54                 context.report({
  55                     node: firstTokenOfBody,
  56                     messageId: "expected",
  57                     fix: fixer => fixer.insertTextBefore(firstTokenOfBody, "\n")
  58                 });
  59             } else if (arrowToken.loc.end.line !== firstTokenOfBody.loc.start.line && option === "beside") {
  60                 context.report({
  61                     node: firstTokenOfBody,
  62                     messageId: "unexpected",
  63                     fix(fixer) {
  64                         if (sourceCode.getFirstTokenBetween(arrowToken, firstTokenOfBody, { includeComments: true, filter: isCommentToken })) {
  65                             return null;
  66                         }
  67
  68                         return fixer.replaceTextRange([arrowToken.range[1], firstTokenOfBody.range[0]], " ");
  69                     }
  70                 });
  71             }
  72         }
  73
  74         //----------------------------------------------------------------------
  75         // Public
  76         //----------------------------------------------------------------------
  77         return {
  78             ArrowFunctionExpression: node => validateExpression(node)
  79         };
  80     }
  81 };