Initial implementation, tests, readme

.eslintrc

@@ -0,0 +1,15 @@
+{
+	"root": true,
+
+	"extends": "@ljharb",
+
+	"rules": {
+		"id-length": "off",
+		"max-lines-per-function": "off",
+		"new-cap": ["error", {
+			"capIsNewExceptions": [
+				"GetIntrinsic",
+			],
+		}],
+	},
+}

.github/FUNDING.yml

@@ -0,0 +1,12 @@
+# These are supported funding model platforms
+
+github: [ljharb]
+patreon: # Replace with a single Patreon username
+open_collective: # Replace with a single Open Collective username
+ko_fi: # Replace with a single Ko-fi username
+tidelift: npm/safe-array-concat
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+otechie: # Replace with a single Otechie username
+custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']

.github/workflows/node-aught.yml

@@ -0,0 +1,18 @@
+name: 'Tests: node.js < 10'
+
+on: [pull_request, push]
+
+jobs:
+  tests:
+    uses: ljharb/actions/.github/workflows/node.yml@main
+    with:
+      range: '< 10'
+      type: minors
+      command: npm run tests-only
+
+  node:
+    name: 'node < 10'
+    needs: [tests]
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo tests completed'

.github/workflows/node-pretest.yml

@@ -0,0 +1,7 @@
+name: 'Tests: pretest/posttest'
+
+on: [pull_request, push]
+
+jobs:
+  tests:
+    uses: ljharb/actions/.github/workflows/pretest.yml@main

.github/workflows/node-tens.yml

@@ -0,0 +1,18 @@
+name: 'Tests: node.js >= 10'
+
+on: [pull_request, push]
+
+jobs:
+  tests:
+    uses: ljharb/actions/.github/workflows/node.yml@main
+    with:
+      range: '>= 10'
+      type: minors
+      command: npm run tests-only
+
+  node:
+    name: 'node >= 10'
+    needs: [tests]
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo tests completed'

.github/workflows/rebase.yml

@@ -0,0 +1,22 @@
+name: Automatic Rebase
+
+on: [pull_request_target]
+
+permissions:
+  contents: read
+
+jobs:
+  _:
+    permissions:
+      contents: write  # for ljharb/rebase to push code to rebase
+      pull-requests: read  # for ljharb/rebase to get info about PR
+
+    name: "Automatic Rebase"
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ljharb/rebase@master
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/require-allow-edits.yml

@@ -0,0 +1,12 @@
+name: Require “Allow Edits”
+
+on: [pull_request_target]
+
+jobs:
+  _:
+    name: "Require “Allow Edits”"
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: ljharb/require-allow-edits@main

.gitignore

@@ -107,3 +107,5 @@ dist
 npm-shrinkwrap.json
 package-lock.json
 yarn.lock
+
+.npmignore

.nycrc

@@ -0,0 +1,13 @@
+{
+	"all": true,
+	"check-coverage": false,
+	"reporter": ["text-summary", "text", "html", "json"],
+	"lines": 86,
+	"statements": 85.93,
+	"functions": 82.43,
+	"branches": 76.06,
+	"exclude": [
+		"coverage",
+		"test"
+	]
+}

README.md

@@ -1,2 +1,53 @@
-# safe-array-concat
-Array.prototype.concat, but is safe by ignoring Symbol.isConcatSpreadable
+# safe-array-concat <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
+
+[![github actions][actions-image]][actions-url]
+[![coverage][codecov-image]][codecov-url]
+[![License][license-image]][license-url]
+[![Downloads][downloads-image]][downloads-url]
+
+[![npm badge][npm-badge-png]][package-url]
+
+`Array.prototype.concat`, but made safe by ignoring Symbol.isConcatSpreadable
+
+## Getting started
+
+```sh
+npm install --save safe-array-concat
+```
+
+## Usage/Examples
+
+```js
+var safeConcat = require('safe-array-concat');
+var assert = require('assert');
+
+assert.deepEqual([].concat([1, 2], 3, [[4]]), [1, 2, 3, [4]], 'arrays spread as expected with normal concat');
+assert.deepEqual(safeConcat([1, 2], 3, [[4]]), [1, 2, 3, [4]], 'arrays spread as expected with safe concat');
+
+String.prototype[Symbol.isConcatSpreadable] = true;
+assert.deepEqual([].concat('foo', Object('bar')), ['foo', 'b', 'a', 'r'], 'spreadable String objects are spread with normal concat!!!');
+assert.deepEqual(safeConcat('foo', Object('bar')), ['foo', Object('bar')], 'spreadable String objects are not spread with safe concat');
+
+Array.prototype[Symbol.isConcatSpreadable] = false;
+assert.deepEqual([].concat([1, 2], 3, [[4]]), [[], [1, 2], 3, [[4]]], 'non-concat-spreadable arrays do not spread with normal concat!!!');
+assert.deepEqual(safeConcat([1, 2], 3, [[4]]), [1, 2, 3, [4]], 'non-concat-spreadable arrays still spread with safe concat');
+```
+
+## Tests
+Simply clone the repo, `npm install`, and run `npm test`
+
+[package-url]: https://npmjs.org/package/safe-array-concat
+[npm-version-svg]: https://versionbadg.es/ljharb/safe-array-concat.svg
+[deps-svg]: https://david-dm.org/ljharb/safe-array-concat.svg
+[deps-url]: https://david-dm.org/ljharb/safe-array-concat
+[dev-deps-svg]: https://david-dm.org/ljharb/safe-array-concat/dev-status.svg
+[dev-deps-url]: https://david-dm.org/ljharb/safe-array-concat#info=devDependencies
+[npm-badge-png]: https://nodei.co/npm/safe-array-concat.png?downloads=true&stars=true
+[license-image]: https://img.shields.io/npm/l/safe-array-concat.svg
+[license-url]: LICENSE
+[downloads-image]: https://img.shields.io/npm/dm/safe-array-concat.svg
+[downloads-url]: https://npm-stat.com/charts.html?package=safe-array-concat
+[codecov-image]: https://codecov.io/gh/ljharb/safe-array-concat/branch/main/graphs/badge.svg
+[codecov-url]: https://app.codecov.io/gh/ljharb/safe-array-concat/
+[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/ljharb/safe-array-concat
+[actions-url]: https://github.com/ljharb/safe-array-concat/actions

index.js

@@ -0,0 +1,36 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+var $concat = GetIntrinsic('%Array.prototype.concat%');
+
+var callBind = require('call-bind');
+
+var callBound = require('call-bind/callBound');
+var $slice = callBound('Array.prototype.slice');
+
+var hasSymbols = require('has-symbols/shams')();
+var isConcatSpreadable = hasSymbols && Symbol.isConcatSpreadable;
+
+var empty = [];
+if (isConcatSpreadable) {
+	empty[isConcatSpreadable] = true;
+}
+var $concatApply = isConcatSpreadable ? callBind.apply($concat, empty) : null;
+var $concatCall = isConcatSpreadable ? null : callBind($concat, empty);
+
+var isArray = isConcatSpreadable ? require('isarray') : null;
+
+module.exports = isConcatSpreadable
+	// eslint-disable-next-line no-unused-vars
+	? function safeArrayConcat(item) {
+		for (var i = 0; i < arguments.length; i += 1) {
+			var arg = arguments[i];
+			if (arg && typeof arg === 'object' && typeof arg[isConcatSpreadable] === 'boolean') {
+				var arr = isArray(arg) ? $slice(arg) : [arg];
+				arr[isConcatSpreadable] = true; // shadow the property. TODO: use [[Define]]
+				arguments[i] = arr;
+			}
+		}
+		return $concatApply(arguments);
+	}
+	: $concatCall;

package.json

@@ -1,19 +1,36 @@
 {
 	"name": "safe-array-concat",
 	"version": "0.0.0",
-	"description": "Array.prototype.concat, but is safe by ignoring Symbol.isConcatSpreadable",
+	"description": "`Array.prototype.concat`, but made safe by ignoring Symbol.isConcatSpreadable",
 	"main": "index.js",
+	"exports": {
+		".": "./index.js",
+		"./package.json": "./package.json"
+	},
 	"scripts": {
-		"test": "echo \"Error: no test specified\" && exit 1"
+		"prepack": "npmignore --auto --commentLines=autogenerated",
+		"version": "auto-changelog && git add CHANGELOG.md",
+		"postversion": "auto-changelog && git add CHANGELOG.md && git commit --no-edit --amend && git tag -f \"v$(node -e \"console.log(require('./package.json').version)\")\"",
+		"lint": "eslint --ext=js,mjs .",
+		"postlint": "evalmd README.md",
+		"prepublish": "not-in-publish || npm run prepublishOnly",
+		"prepublishOnly": "safe-publish-latest",
+		"pretest": "npm run lint",
+		"tests-only": "nyc tape test",
+		"test": "npm run tests-only",
+		"posttest": "aud --production"
 	},
 	"keywords": [
 		"safe",
-		"array",
+		"Array",
 		"concat",
 		"push",
-		"isconcatspreadable"
+		"isConcatSpreadable"
 	],
 	"author": "Jordan Harband <ljharb@gmail.com>",
+	"funding": {
+		"url": "https://github.com/sponsors/ljharb"
+	},
 	"license": "MIT",
 	"repository": {
 		"type": "git",
@@ -22,5 +39,40 @@
 	"bugs": {
 		"url": "https://github.com/ljharb/safe-array-concat/issues"
 	},
-	"homepage": "https://github.com/ljharb/safe-array-concat#readme"
+	"homepage": "https://github.com/ljharb/safe-array-concat#readme",
+	"devDependencies": {
+		"@ljharb/eslint-config": "^21.0.1",
+		"aud": "^2.0.2",
+		"auto-changelog": "^2.4.0",
+		"eslint": "=8.8.0",
+		"evalmd": "^0.0.19",
+		"in-publish": "^2.0.1",
+		"mock-property": "^1.0.0",
+		"npmignore": "^0.3.0",
+		"nyc": "^10.3.2",
+		"safe-publish-latest": "^2.0.0",
+		"tape": "^5.6.3"
+	},
+	"dependencies": {
+		"call-bind": "^1.0.2",
+		"get-intrinsic": "^1.2.0",
+		"has-symbols": "^1.0.3",
+		"isarray": "^2.0.5"
+	},
+	"auto-changelog": {
+		"output": "CHANGELOG.md",
+		"template": "keepachangelog",
+		"unreleased": false,
+		"commitLimit": false,
+		"backfillLimit": false,
+		"hideCredit": true
+	},
+	"publishConfig": {
+		"ignore": [
+			".github/workflows"
+		]
+	},
+	"engines": {
+		"node": ">=0.4"
+	}
 }

test/index.js

@@ -0,0 +1,89 @@
+'use strict';
+
+var test = require('tape');
+var mockProperty = require('mock-property');
+var hasSymbols = require('has-symbols/shams')();
+var isConcatSpreadable = hasSymbols && Symbol.isConcatSpreadable;
+var species = hasSymbols && Symbol.species;
+
+var boundFnsHaveConfigurableLengths = Object.getOwnPropertyDescriptor && Object.getOwnPropertyDescriptor(function () {}.bind(), 'length').configurable;
+
+var safeConcat = require('../');
+
+test('safe-array-concat', function (t) {
+	t.equal(typeof safeConcat, 'function', 'is a function');
+	t.equal(
+		safeConcat.length,
+		boundFnsHaveConfigurableLengths ? 1 : 0,
+		'has a length of ' + (boundFnsHaveConfigurableLengths ? 1 : '0 (function lengths are not configurable)'),
+		'length is as expected'
+	);
+
+	t.deepEqual(
+		safeConcat([1, 2], [3, 4], 'foo', 5, 6, [[7]]),
+		[1, 2, 3, 4, 'foo', 5, 6, [7]],
+		'works with flat and nested arrays'
+	);
+
+	t.deepEqual(
+		safeConcat(undefined, 1, 2),
+		[undefined, 1, 2],
+		'first item as undefined is not the concat receiver, which would throw via ToObject'
+	);
+	t.deepEqual(
+		safeConcat(null, 1, 2),
+		[null, 1, 2],
+		'first item as null is not the concat receiver, which would throw via ToObject'
+	);
+
+	var arr = [1, 2];
+	arr.constructor = function C() {
+		return { args: arguments };
+	};
+	t.deepEqual(
+		safeConcat(arr, 3, 4),
+		[1, 2, 3, 4],
+		'first item as an array with a nonArray .constructor; ignores constructor'
+	);
+
+	t.test('has Symbol.species', { skip: !species }, function (st) {
+		var speciesArr = [1, 2];
+		speciesArr.constructor = {};
+		speciesArr.constructor[species] = function Species() {
+			return { args: arguments };
+		};
+
+		st.deepEqual(
+			safeConcat(speciesArr, 3, 4),
+			[1, 2, 3, 4],
+			'first item as an array with a .constructor object with a Symbol.species; ignores constructor and species'
+		);
+
+		st.end();
+	});
+
+	t.test('has isConcatSpreadable', { skip: !isConcatSpreadable }, function (st) {
+		st.teardown(mockProperty(String.prototype, isConcatSpreadable, { value: true }));
+
+		var nonSpreadable = [1, 2];
+		nonSpreadable[isConcatSpreadable] = false;
+
+		st.deepEqual(
+			safeConcat(nonSpreadable, 3, 4, 'foo', Object('bar')),
+			[1, 2, 3, 4, 'foo', Object('bar')],
+			'a non-concat-spreadable array is spreaded, and a concat-spreadable String is not spreaded'
+		);
+
+		st.teardown(mockProperty(Array.prototype, isConcatSpreadable, { value: false }));
+
+		st.deepEqual(
+			safeConcat([1, 2], 3, 4, 'foo', Object('bar')),
+			[1, 2, 3, 4, 'foo', Object('bar')],
+			'all arrays marked non-concat-spreadable are still spreaded, and a concat-spreadable String is not spreaded'
+		);
+
+		st.end();
+	});
+
+	t.end();
+});