[eslint] add linting

Author: ljharb

.eslintrc

@@ -0,0 +1,28 @@
+{
+	"root": true,
+
+	"extends": "@ljharb",
+
+	"rules": {
+		"id-length": "off",
+		"new-cap": ["error", {
+			"capIsNewExceptions": [
+				"StringCharCodeAt",
+				"RequireObjectCoercible",
+				"ToInteger",
+				"ToString",
+			],
+		}],
+		"no-magic-numbers": "off",
+	},
+
+	"overrides": [
+		{
+			"files": ["tests/**/*"],
+			"rules": {
+				"max-lines-per-function": "off",
+				"max-statements-per-line": "off",
+			},
+		},
+	]
+}

auto.js

@@ -1,3 +1,5 @@
 /*! https://mths.be/codepointat v1.0.0 by @mathias */
 
+'use strict';
+
 require('./shim')();

implementation.js

@@ -21,13 +21,13 @@ module.exports = function codePointAt(position) {
 	var first = StringCharCodeAt(string, index);
 	var second;
 	if ( // check if it’s the start of a surrogate pair
-		first >= 0xD800 && first <= 0xDBFF && // high surrogate
-		size > index + 1 // there is a next code unit
+		first >= 0xD800 && first <= 0xDBFF // high surrogate
+		&& size > index + 1 // there is a next code unit
 	) {
 		second = StringCharCodeAt(string, index + 1);
 		if (second >= 0xDC00 && second <= 0xDFFF) { // low surrogate
 			// https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
-			return (first - 0xD800) * 0x400 + second - 0xDC00 + 0x10000;
+			return ((first - 0xD800) * 0x400) + second - 0xDC00 + 0x10000;
 		}
 	}
 	return first;

package.json

@@ -30,7 +30,9 @@
 	},
 	"bugs": "https://github.com/mathiasbynens/String.prototype.codePointAt/issues",
 	"scripts": {
-		"pretest": "es-shim-api --bound",
+		"lint": "eslint --ext=js,mjs .",
+		"postlint": "es-shim-api --bound",
+		"pretest": "npm run lint",
 		"test": "npm run tests-only",
 		"tests-only": "tape 'tests/*.js'",
 		"posttest": "npx npm@'>=10.2' audit --production",
@@ -41,7 +43,9 @@
 	},
 	"devDependencies": {
 		"@es-shims/api": "^2.5.1",
+		"@ljharb/eslint-config": "^21.1.1",
 		"define-properties": "^1.2.1",
+		"eslint": "=8.8.0",
 		"function-bind": "^1.1.2",
 		"functions-have-names": "^1.2.3",
 		"has-strict-mode": "^1.0.1",

shim.js

@@ -14,4 +14,4 @@ module.exports = function shimCodePointAt() {
 	}
 
 	return polyfill;
-}
+};

tests/tests.js

@@ -2,7 +2,7 @@
 
 var supportsStrictMode = require('has-strict-mode')();
 
-module.exports = function (codePointAt, t) {	
+module.exports = function (codePointAt, t) {
 	t.test('String that starts with a BMP symbol', function (st) {
 		st.equal(codePointAt('abc\uD834\uDF06def', -1), undefined);
 		st.equal(codePointAt('abc\uD834\uDF06def', -0), 0x61);
@@ -89,14 +89,14 @@ module.exports = function (codePointAt, t) {
 		st['throws'](function () { return codePointAt(null, 'a'); }, TypeError, 'null is not an object');
 		st.end();
 	});
-	
+
 	t.test('cast this value', function (st) {
 		st.equal(codePointAt(42, 0), 0x34);
 		st.equal(codePointAt(42, 1), 0x32);
-		st.equal(codePointAt({ 'toString': function() { return 'abc'; } }, 2), 0x63);
+		st.equal(codePointAt({ toString: function () { return 'abc'; } }, 2), 0x63);
 
 		var tmp = 0;
-		st.equal(codePointAt({ 'toString': function() { ++tmp; return String(tmp); } }, 0), 0x31);
+		st.equal(codePointAt({ toString: function () { tmp += 1; return String(tmp); } }, 0), 0x31);
 		st.equal(tmp, 1);
 
 		st.end();