Use explicit extensions for imports within src

.eslintrc.json

@@ -144,7 +144,8 @@
  "local/no-in-operator": "error",
  "local/debug-assert": "error",
  "local/no-keywords": "error",
- "local/jsdoc-format": "error"
+ "local/jsdoc-format": "error",
+ "local/js-extensions": "error"
  },
  "overrides": [
  // By default, the ESLint CLI only looks at .js files. But, it will also look at

scripts/eslint/rules/js-extensions.cjs

@@ -0,0 +1,55 @@
+const { createRule } = require("./utils.cjs");
+
+/** @typedef {import("@typescript-eslint/utils").TSESTree.ImportDeclaration | import("@typescript-eslint/utils").TSESTree.ExportAllDeclaration | import("@typescript-eslint/utils").TSESTree.ExportNamedDeclaration | import("@typescript-eslint/utils").TSESTree.TSImportEqualsDeclaration} ImportOrExport */
+
+module.exports = createRule({
+ name: "js-extensions",
+ meta: {
+ docs: {
+ description: ``,
+ },
+ messages: {
+ missingJsExtension: `This relative import is missing a '.js' extension`,
+ },
+ schema: [],
+ type: "suggestion",
+ fixable: "code",
+ },
+ defaultOptions: [],
+
+ create(context) {
+ /** @type {(node: ImportOrExport) => void} */
+ const check = node => {
+ let source;
+ if (node.type === "TSImportEqualsDeclaration") {
+ const moduleReference = node.moduleReference;
+ if (
+ moduleReference.type === "TSExternalModuleReference"
+ && moduleReference.expression.type === "Literal"
+ && typeof moduleReference.expression.value === "string"
+ ) {
+ source = moduleReference.expression;
+ }
+ }
+ else {
+ source = node.source;
+ }
+
+ if (source?.value.startsWith(".") && !/\.[cm]?js$/.test(source.value)) {
+ const quote = source.raw[0];
+ context.report({
+ messageId: "missingJsExtension",
+ node: source,
+ fix: fixer => fixer.replaceText(source, `${quote}${source.value}.js${quote}`),
+ });
+ }
+ };
+
+ return {
+ ImportDeclaration: check,
+ ExportAllDeclaration: check,
+ ExportNamedDeclaration: check,
+ TSImportEqualsDeclaration: check,
+ };
+ },
+});

scripts/eslint/tests/js-extensions.cjs

@@ -0,0 +1,149 @@
+const { RuleTester } = require("./support/RuleTester.cjs");
+const rule = require("../rules/js-extensions.cjs");
+
+const ruleTester = new RuleTester({
+ parserOptions: {
+ warnOnUnsupportedTypeScriptVersion: false,
+ },
+ parser: require.resolve("@typescript-eslint/parser"),
+});
+
+ruleTester.run("js-extensions", rule, {
+ valid: [
+ {
+ code: `
+import "some-library";
+import "./a.js";
+import "./a.mjs";
+import "./a.cjs";
+import "../foo/a.js";
+import "../foo/a.mjs";
+import "../foo/a.cjs";
+ `,
+ },
+ {
+ code: `
+import * as blah from "some-library";
+import * as blah from "./a.js";
+import * as blah from "./a.mjs";
+import * as blah from "./a.cjs";
+import * as blah from "../foo/a.js";
+import * as blah from "../foo/a.mjs";
+import * as blah from "../foo/a.cjs";
+ `,
+ },
+ {
+ code: `
+export * from "some-library";
+export * from "./a.js";
+export * from "./a.mjs";
+export * from "./a.cjs";
+export * from "../foo/a.js";
+export * from "../foo/a.mjs";
+export * from "../foo/a.cjs";
+ `,
+ },
+ {
+ code: `
+import blah = require("some-library");
+import blah = require("./a.js");
+import blah = require("./a.mjs");
+import blah = require("./a.cjs");
+import blah = require("../foo/a.js");
+import blah = require("../foo/a.mjs");
+import blah = require("../foo/a.cjs");
+ `,
+ },
+ ],
+
+ invalid: [
+ {
+ code: `
+import "./a";
+import "../foo/a";
+ `,
+ errors: [
+ {
+ messageId: "missingJsExtension",
+ line: 2,
+ column: 8,
+ },
+ {
+ messageId: "missingJsExtension",
+ line: 3,
+ column: 8,
+ },
+ ],
+ output: `
+import "./a.js";
+import "../foo/a.js";
+ `,
+ },
+ {
+ code: `
+import * as blah from "./a";
+import * as blah from "../foo/a";
+ `,
+ errors: [
+ {
+ messageId: "missingJsExtension",
+ line: 2,
+ column: 23,
+ },
+ {
+ messageId: "missingJsExtension",
+ line: 3,
+ column: 23,
+ },
+ ],
+ output: `
+import * as blah from "./a.js";
+import * as blah from "../foo/a.js";
+ `,
+ },
+ {
+ code: `
+export * from "./a";
+export * from "../foo/a";
+ `,
+ errors: [
+ {
+ messageId: "missingJsExtension",
+ line: 2,
+ column: 15,
+ },
+ {
+ messageId: "missingJsExtension",
+ line: 3,
+ column: 15,
+ },
+ ],
+ output: `
+export * from "./a.js";
+export * from "../foo/a.js";
+ `,
+ },
+ {
+ code: `
+import blah = require("./a");
+import blah = require("../foo/a");
+ `,
+ errors: [
+ {
+ messageId: "missingJsExtension",
+ line: 2,
+ column: 23,
+ },
+ {
+ messageId: "missingJsExtension",
+ line: 3,
+ column: 23,
+ },
+ ],
+ output: `
+import blah = require("./a.js");
+import blah = require("../foo/a.js");
+ `,
+ },
+ ],
+});