2c:null 2d:["$","title",null,{"children":"ECMAScript 6+ (2015-2022) | Robert Batty | Observable"}] 32:[] 30:{"id":"39b098d4e8cc5ede","slug":"ecmascript-2015-2022","title":"ECMAScript 6+ (2015-2022)","thumbnail":"ce730c113bbd5a119b2966bfa3bb929af6b0184db1a3008a0a7efe13cb0d9dde","access_level":"public","create_time":"$D2022-08-25T20:18:12.197Z","update_time":"$D2022-09-14T15:29:26.758Z","view_time":null,"first_public_time":"$D2022-08-27T05:08:15.086Z","has_unpublished_edits":null,"fork":false,"stars":4,"starred":false,"owner":{"type":"team","id":"b6221ba902bfc582","login":"robertbatty","name":"Robert Batty","avatar_url":"https://avatars-next.observableusercontent.com/9e1a94f97db2169519ef196abb770ca7706e7b9c1f754526607a1f879f0dacb6","tier":"starter_2024","bio":""},"version":573,"publish_version":573,"role":null,"authored":false,"authors":[{"type":"individual","id":"659e066240c21c78","login":"robertbatty","name":"Robert Batty","avatar_url":"https://avatars-next.observableusercontent.com/9e1a94f97db2169519ef196abb770ca7706e7b9c1f754526607a1f879f0dacb6","tier":null,"bio":""}],"members":[{"type":"individual","id":"659e066240c21c78","login":"robertbatty","name":"Robert Batty","avatar_url":"https://avatars-next.observableusercontent.com/9e1a94f97db2169519ef196abb770ca7706e7b9c1f754526607a1f879f0dacb6","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":true,"trashed":false,"lapsed":null,"subscribed":null,"forks":1,"collection":{"id":"055b25992b60b271","slug":"docs-articles","title":"Docs, Articles","owner":{"id":"b6221ba902bfc582","login":"robertbatty","name":"Robert Batty"}},"type":"notebook","body":{"titling":"auto","title":"ECMAScript 6+ (2015-2022)","cells":[{"id":0,"value":"# ECMAScript 6+ (2015-2022)\n\nFeatures from ECMAScript, My Highlights by Year","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":540,"value":"toc({ ignoreFirst: true })","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":274,"value":"# ES6 (2015)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":479,"value":"Features:\n\n- Functions\n - Default Params (Function)\n - Template Literals\n- Objects\n - Spread Syntax (Spread Operator for `Array`)\n - Destructuring\n - Object Assing\n- Let & Const\n- Modules & Generators\n","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":423,"value":"### Template Literals","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":425,"value":"{\n const a = 5;\n const b = 10;\n return `Fifteen is ${a + b} and not ${2 * a + b}.`;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":334,"value":"### Object Assing\n~~~~ts\nObject.assing(Object, Object): Object\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":9,"value":"Object.assign({ a: 1, b: 41 }, { a: 2, c: 30 })","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":516,"value":"### Spread Syntax (Array)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":572,"value":"Spread syntax (...) allows an iterable, such as an array or string, to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":565,"value":"...","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":272,"value":"# ES7 (2016)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":487,"value":"Features:\n- Exponential Operator\n- Includes","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":15,"value":"### Exponential Operator","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":4,"value":"123 ** 2","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":339,"value":"### Includes\n~~~~ts\nArray.includes(any): Boolean\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":295,"value":"{\n const list = [\"oscar\", \"David\", \"Ana\"];\n // case sensible\n return list.includes(\"Oscar\"); // false\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":298,"value":"{\n let numbers = [1, 3, 4, 6, 7, 8];\n return numbers.includes(7); // true\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":270,"value":"# ES8 (2017)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":483,"value":"Features:\n- Objects:\n - Object Entries\n - Object Keys\n - Object Values\n- Async / Await\n- Trailing Commas","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":362,"value":"obj = ({\n a: \"somestring\",\n b: 42\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":438,"value":"### Async / Await","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":440,"value":"{\n async function f() {\n return Promise.resolve(1);\n }\n\n return await f();\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":343,"value":"### Object Entries\n~~~~ts\nObject.entries(Object): [string, any][] // [ ['key', value], ['key', value], ...]\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":352,"value":"Object.entries(obj)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":373,"value":"### Object Keys\n~~~~ts\nObject.keys(Object): string[] // [ 'key', 'key', ...]\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":375,"value":"Object.keys(obj)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":371,"value":"### Object Values\n~~~~js\nObject.values(obj): any[] // [value, value, ...]\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":359,"value":"Object.values(obj)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":452,"value":"### Trailing Commas\n\n~~~~ts\nconst arr = [\n 1,\n 2,\n 3, // comma at the end, with no error\n];\n\narr; // [1, 2, 3]\narr.length; // 3\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":155,"value":"# ES9 (2018)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":512,"value":"Features:\n- Rest Operator","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":202,"value":"### Rest Operator\n\n","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":198,"value":"{\n /* Operador de reposo / Rest Operator */\n const obj = {\n name: \"santiago\",\n age: 19,\n country: \"CO\"\n };\n\n let { name, ...all } = obj;\n return name, all; // santiago { age: 19, country: 'CO' }\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":262,"value":"# ES10 (2019)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":494,"value":"Features:\n- From Entries\n- Trim","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":222,"value":"### From Entries\n~~~~ts\nObject.fromEntries(map): Object\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":220,"value":"{\n const map = new Map([\n [\"a\", 1],\n [\"b\", 2],\n [\"c\", 3]\n ]);\n const obj = Object.fromEntries(map);\n\n return obj;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":442,"value":"### Trim\n\n~~~~ts\nString.trim(): string\nString.trimStart(): string\nString.trimEnd(): string\n~~~~ ","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":449,"value":"{\n const saludo = \" hola \";\n const result1 = saludo.trim();\n const result2 = saludo.trimStart();\n const result3 = saludo.trimEnd();\n\n return {\n result1,\n result2,\n result3\n };\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":264,"value":"# ES11 (2020)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":499,"value":"Features:\n- Optional Chaining\n- [BigInt](###BigInt)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":409,"value":"### Optional Chaining\n\n~~~~js\nobj?.prop // optional static property access\nobj?.[expr] // optional dynamic property access\nfunc?.(...args) // optional function or method call\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":412,"value":"{\n const adventurer = {\n name: \"Alice\",\n cat: {\n name: \"Dinah\"\n }\n };\n\n const dogName = adventurer.dog?.name;\n dogName;\n // expected output: undefined\n\n adventurer.someNonExistentMethod?.();\n // expected output: undefined\n\n return adventurer?.cat;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":462,"value":"### BigInt","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":527,"value":"> [MDN Docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":464,"value":"{\n const previousMaxSafe = BigInt(Number.MAX_SAFE_INTEGER);\n // ↪ 9007199254740991n\n\n const maxPlusOne = previousMaxSafe + 1n;\n // ↪ 9007199254740992n\n\n const theFuture = previousMaxSafe + 2n;\n // ↪ 9007199254740993n, this works now!\n\n const multi = previousMaxSafe * 2n;\n // ↪ 18014398509481982n\n\n const subtr = multi - 10n;\n // ↪ 18014398509481972n\n\n const mod = multi % 10n;\n // ↪ 2n\n\n const bigN = 2n ** 54n;\n // ↪ 18014398509481984n\n\n return bigN * -1n;\n // ↪ -18014398509481984n\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":266,"value":"# ES12 (2021)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":501,"value":"Features:\n- Logical Assignment Operators","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":396,"value":"### Logical Assignment Operators\n\n","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":305,"value":"{\n let [a, b] = [null, 4];\n // \"Or Or Equals\" (or, the Mallet operator :wink:)\n // a || (a = b);\n return [(a ||= b), (b ||= a)];\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":313,"value":"{\n let [a, b] = [true, 4];\n // \"And And Equals\"\n // a && (a = b);\n return (a &&= b);\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":318,"value":"{\n let [a, b] = [2, 4];\n // \"QQ Equals\"\n // a ?? (a = b);\n return (a ??= b);\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":105,"value":"# ES13 (2022)","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":503,"value":"Features:\n- Array\n - At\n - Find Last\n- Top level `await`","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":149,"value":"### At\n~~~~js\nArray.at(index): any\n~~~~","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":110,"value":"[\"apple\", \"orange\", \"strawberry\"].at(0)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":124,"value":"### Top level `await`\n\nTop-level await enables modules to act as big async functions: With top-level await, ECMAScript Modules (ESM) can await resources, causing other modules who import them to wait before they start evaluating their body.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":116,"value":"{\n const response = await fetch(\"https://api.escuelajs.co/api/v1/products\");\n const products = await response.json();\n\n return { products };\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":167,"value":"### Find Last\n\nFind Last / Find Last Index\n\n~~~~ts\nArray.findLast((item) => Boolean): any\n\nArray.findLastIndex((item) => Boolean): number\n~~~~\n","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":169,"value":"{\n const array = [{ value: 1 }, { value: 2 }, { value: 3 }, { value: 4 }];\n\n array.find((n) => n.value % 2 === 1); // { value: 1 }\n array.findIndex((n) => n.value % 2 === 1); // 0\n\n // ======== Before the proposal ===========\n\n // find\n [...array].reverse().find((n) => n.value % 2 === 1); // { value: 3 }\n\n // findIndex\n array.length - 1 - [...array].reverse().findIndex((n) => n.value % 2 === 1); // 2\n array.length - 1 - [...array].reverse().findIndex((n) => n.value === 42); // should be -1, but 4\n\n // ======== In the proposal ===========\n // find\n return array.findLast((n) => n.value % 2 === 1); // { value: 3 }\n\n // findIndex\n array.findLastIndex((n) => n.value % 2 === 1); // 2\n array.findLastIndex((n) => n.value === 42); // -1\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":68,"value":"signature","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":158,"value":"Biblography\n\n- ECMAScript: Versiones de JavaScript (by Luis Ariza) (Spanish/Español)\n- TC39: Finished Proposals\n- ES6: Features\n- MDN Docs","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"","database":"$undefined"},{"id":63,"value":"import { signature } from \"@robertbatty/signature\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":532,"value":"import { toc } from \"@robertbatty/toc\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W32","stdlib":"1"}} 31:"$30:body"