feat: added support for regexp literal (#644)

Author: DenyVeyten

src/constants.ts

@@ -54,4 +54,5 @@ export enum AstNodeTypes {
   MemberExpression = "MemberExpression",
   CallExpression = "CallExpression",
   NewExpression = "NewExpression",
+  Literal = "Literal",
 }

src/helpers.ts

@@ -1,16 +1,16 @@
 /* eslint no-nested-ternary: off */
 import browserslist from "browserslist";
+import { AstNodeTypes, TargetNameMappings } from "./constants";
 import {
   AstMetadataApiWithTargetsResolver,
+  BrowserListConfig,
+  BrowsersListOpts,
+  Context,
   ESLintNode,
+  HandleFailingRule,
   SourceCode,
-  BrowserListConfig,
   Target,
-  HandleFailingRule,
-  Context,
-  BrowsersListOpts,
 } from "./types";
-import { TargetNameMappings } from "./constants";
 
 /*
 3) Figures out which browsers user is targeting
@@ -109,8 +109,31 @@ export function lintExpressionStatement(
     );
 }
 
+function checkRegexpLiteral(node: ESLintNode): boolean {
+  return (
+    node.type === AstNodeTypes.Literal &&
+    (!!node.regex || node.parent?.callee?.name === "RegExp")
+  );
+}
+
+export function lintLiteral(
+  context: Context,
+  handleFailingRule: HandleFailingRule,
+  rules: AstMetadataApiWithTargetsResolver[],
+  sourceCode: SourceCode,
+  node: ESLintNode
+) {
+  const isRegexpLiteral = checkRegexpLiteral(node);
+  const failingRule = rules.find((rule) =>
+    rule.syntaxes?.some(
+      (syntax) => (isRegexpLiteral ? node.raw.includes(syntax) : false) // non-regexp literals are not supported yet
+    )
+  );
+  if (failingRule) handleFailingRule(failingRule, node);
+}
+
 function isStringLiteral(node: ESLintNode): boolean {
-  return node.type === "Literal" && typeof node.value === "string";
+  return node.type === AstNodeTypes.Literal && typeof node.value === "string";
 }
 
 function protoChainFromMemberExpression(node: ESLintNode): string[] {

src/index.ts

@@ -6,9 +6,9 @@
 //------------------------------------------------------------------------------
 // Requirements
 //------------------------------------------------------------------------------
-import recommended from "./config/recommended";
-import pkg from "../package.json";
 import type { Linter } from "eslint";
+import pkg from "../package.json";
+import recommended from "./config/recommended";
 
 //------------------------------------------------------------------------------
 // Plugin Definition
@@ -32,7 +32,7 @@ const plugin = {
 
 const configs = {
   "flat/recommended": {
-    name: 'compat/flat/recommended',
+    name: "compat/flat/recommended",
     plugins: { compat: plugin },
     ...recommended.flat,
   } as Linter.FlatConfig,

src/providers/caniuse-provider.ts

@@ -1,5 +1,5 @@
 import * as lite from "caniuse-lite";
-import { STANDARD_TARGET_NAME_MAPPING, AstNodeTypes } from "../constants";
+import { AstNodeTypes, STANDARD_TARGET_NAME_MAPPING } from "../constants";
 import { AstMetadataApiWithTargetsResolver, Target } from "../types";
 
 /**
@@ -241,6 +241,13 @@ const CanIUseProvider: Array<AstMetadataApiWithTargetsResolver> = [
     astNodeType: AstNodeTypes.NewExpression,
     object: "Float64Array",
   },
+  {
+    caniuseId: "js-regexp-lookbehind",
+    astNodeType: AstNodeTypes.Literal,
+    name: "Lookbehind",
+    object: "RegExp",
+    syntaxes: ["?<=", "?<!"],
+  },
 ].map((rule) => ({
   ...rule,
   getUnsupportedTargets,

src/rules/compat.ts

@@ -5,27 +5,28 @@
  *   Tells eslint to lint certain nodes  (lintCallExpression, lintMemberExpression, lintNewExpression)
  *   Gets protochain for the ESLint nodes the plugin is interested in
  */
-import fs from "fs";
+import { Rule } from "eslint";
 import findUp from "find-up";
+import fs from "fs";
 import memoize from "lodash.memoize";
-import { Rule } from "eslint";
 import {
+  determineTargetsFromConfig,
   lintCallExpression,
+  lintExpressionStatement,
+  lintLiteral,
   lintMemberExpression,
   lintNewExpression,
-  lintExpressionStatement,
   parseBrowsersListVersion,
-  determineTargetsFromConfig,
 } from "../helpers"; // will be deprecated and introduced to this file
+import { nodes } from "../providers";
 import {
-  ESLintNode,
   AstMetadataApiWithTargetsResolver,
   BrowserListConfig,
-  HandleFailingRule,
-  Context,
   BrowsersListOpts,
+  Context,
+  ESLintNode,
+  HandleFailingRule,
 } from "../types";
-import { nodes } from "../providers";
 
 type ESLint = {
   [astNodeTypeName: string]: (node: ESLintNode) => void;
@@ -45,6 +46,9 @@ function getName(node: ESLintNode): string {
     case "CallExpression": {
       return node.callee!.name;
     }
+    case "Literal": {
+      return node.type;
+    }
     default:
       throw new Error("not found");
   }
@@ -110,6 +114,7 @@ type RulesFilteredByTargets = {
   NewExpression: AstMetadataApiWithTargetsResolver[];
   MemberExpression: AstMetadataApiWithTargetsResolver[];
   ExpressionStatement: AstMetadataApiWithTargetsResolver[];
+  Literal: AstMetadataApiWithTargetsResolver[];
 };
 
 /**
@@ -124,6 +129,7 @@ const getRulesForTargets = memoize(
       NewExpression: [] as AstMetadataApiWithTargetsResolver[],
       MemberExpression: [] as AstMetadataApiWithTargetsResolver[],
       ExpressionStatement: [] as AstMetadataApiWithTargetsResolver[],
+      Literal: [] as AstMetadataApiWithTargetsResolver[],
     };
     const targets = JSON.parse(targetsJSON);
 
@@ -248,6 +254,13 @@ export default {
         ],
         sourceCode
       ),
+      Literal: lintLiteral.bind(
+        null,
+        context,
+        handleFailingRule,
+        targetedRules.Literal,
+        sourceCode
+      ),
       // Keep track of all the defined variables. Do not report errors for nodes that are not defined
       Identifier(node: ESLintNode) {
         if (node.parent) {

src/types.ts

@@ -1,7 +1,7 @@
 import { APIKind } from "ast-metadata-inferer/lib/types";
+import type { Options as DefaultBrowsersListOpts } from "browserslist";
 import { Rule } from "eslint";
 import { TargetNameMappings } from "./constants";
-import type { Options as DefaultBrowsersListOpts } from "browserslist";
 
 export type BrowserListConfig =
   | string
@@ -18,8 +18,13 @@ type AstMetadataApi = {
   type?: string;
   name?: string;
   object: string;
-  astNodeType: "MemberExpression" | "CallExpression" | "NewExpression";
+  astNodeType:
+    | "MemberExpression"
+    | "CallExpression"
+    | "NewExpression"
+    | "Literal";
   property?: string;
+  syntaxes?: string[];
   protoChainId: string;
   protoChain: Array<string>;
 };
@@ -49,6 +54,11 @@ export type ESLintNode = {
     name: string;
     type?: string;
   };
+  regex?: {
+    flags: string;
+    pattern: string;
+  };
+  raw: string;
 };
 
 export type SourceCode = import("eslint").SourceCode;

test/e2e.spec.ts

@@ -1,6 +1,6 @@
 import { RuleTester } from "eslint";
-import rule from "../src/rules/compat";
 import { parser } from "typescript-eslint";
+import rule from "../src/rules/compat";
 
 const ruleTester = new RuleTester({
   languageOptions: {
@@ -691,5 +691,21 @@ ruleTester.run("compat", rule, {
         },
       ],
     },
+    {
+      code: "/(?<=y)x/, new RegExp('(?<!y)x'), 'x', true, false, null, 1, 0n",
+      settings: {
+        browsers: ["Safari >= 16.3", "iOS >= 16.3"],
+      },
+      errors: [
+        {
+          message:
+            "Lookbehind is not supported in Safari 16.3, iOS Safari 16.3",
+        },
+        {
+          message:
+            "Lookbehind is not supported in Safari 16.3, iOS Safari 16.3",
+        },
+      ],
+    },
   ],
 });