Meta tags:
Headings (most frequently used words):
and, tools, in, client, usage, other, navigation, the, of, examples, vulnerabilities, misplaced, trust, errors, javascript, contents, history, trademark, website, side, features, syntax, security, development, related, technologies, references, further, reading, external, links, menu, creation, at, netscape, adoption, by, microsoft, rise, jscript, growth, standardization, reaching, maturity, scripted, behavior, libraries, frameworks, imperative, structured, weakly, typed, dynamic, object, orientation, prototype, based, functional, delegative, miscellaneous, vendor, specific, extensions, simple, more, advanced, example, cross, site, developers, browser, plugin, coding, sandbox, implementation, hardware, java, json, typescript, webassembly, transpilers, personal, namespaces, views, contribute, print, export, projects, languages,
Text of the page (most frequently used words):
the (450), #javascript (197), and (153), from (115), archived (91), function (85), retrieved (81), for (81), this (79), original (76), with (75), object (61), web (57), can (56), that (53), are (50), 2021 (46), ecmascript (37), not (35), browser (34), code (32), was (30), prototype (30), language (30), july (29), other (28), 2018 (27), new (27), 2017 (26), based (25), mozilla (25), libraries (24), microsoft (24), java (24), com (24), const (24), have (24), may (23), programming (23), return (23), functions (23), such (23), internet (22), side (22), august (22), languages (21), 2013 (21), 2020 (21), let (21), returns (21), using (20), also (20), june (20), objects (20), value (20), string (20), site (19), client (19), like (19), which (19), page (18), december (18), wayback (18), data (18), syntax (18), number (18), articles (17), example (17), created (17), netscape (17), server (17), machine (17), lcm (17), node (16), explorer (16), browsers (16), eich (16), february (16), their (16), has (16), gcd (16), 2022 (15), all (15), standard (15), jscript (15), document (15), first (15), 2015 (15), used (15), non (14), scripting (14), 2016 (14), websites (14), class (14), only (14), developers (13), april (13), security (13), most (13), one (13), console (13), while (13), when (13), methods (13), radius (13), time (13), wikipedia (12), use (12), frameworks (12), brendan (12), library (12), property (12), 2019 (12), properties (12), usage (12), they (12), were (12), these (12), run (12), method (12), output (12), array (12), constructor (12), source (11), html (11), features (11), ecma (11), 2011 (11), 2012 (11), 2009 (11), developer (11), many (11), its (11), any (11), lcmcalculator (11), variable (11), name (11), empty (11), links (10), export (10), pages (10), march (10), google (10), firefox (10), 2014 (10), isbn (10), specification (10), january (10), scripts (10), both (10), some (10), vulnerabilities (10), obj (10), arrow (10), related (9), more (9), log (9), create (9), cross (9), org (9), next (9), via (9), november (9), script (9), work (9), variables (9), defined (9), but (9), including (9), implementation (9), user (9), will (9), each (9), operator (9), import (9), information (8), here (8), identifiers (8), 1995 (8), functional (8), typescript (8), webassembly (8), standards (8), engines (8), 978 (8), add (8), buffer (8), mdn (8), been (8), process (8), same (8), done (8), set (8), called (8), them (8), because (8), website (8), numbers (8), applications (8), sum (8), behavior (8), cast (8), released (8), trademark (7), tools (7), project (7), typed (7), npm (7), dom (7), json (7), multiple (7), years (7), edition (7), see (7), attack (7), 2010 (7), network (7), arguments (7), inheritance (7), release (7), development (7), sandbox (7), two (7), common (7), built (7), privileges (7), another (7), attacker (7), considered (7), xss (7), then (7), without (7), there (7), strings (7), instance (7), false (7), undefined (7), counter (7), expressions (7), keyword (7), input (7), world (7), supports (7), about (6), policy (6), history (6), application (6), safari (6), chrome (6), extensions (6), international (6), comparison (6), visual (6), studio (6), oriented (6), corporation (6), vulnerability (6), users (6), event (6), role (6), prototypes (6), oracle (6), es6 (6), engine (6), now (6), type (6), allow (6), literal (6), typing (6), dynamic (6), math (6), program (6), could (6), practice (6), provides (6), systems (6), upon (6), trust (6), form (6), include (6), provide (6), need (6), instead (6), num2 (6), num1 (6), show (6), myball (6), ball (6), expression (6), introduced (6), creation (6), factorial (6), elements (6), myelem (6), environment (6), similar (6), call (6), text (5), version (5), article (5), software (5), list (5), asynchronous (5), module (5), net (5), actionscript (5), technologies (5), transpilers (5), media (5), press (5), david (5), 2008 (5), make (5), windows (5), docs (5), note (5), overflow (5), access (5), how (5), var (5), september (5), loop (5), github (5), adobe (5), must (5), sun (5), regular (5), general (5), than (5), loaded (5), support (5), classes (5), major (5), flaws (5), system (5), cannot (5), private (5), victim (5), body (5), result (5), instances (5), named (5), often (5), modified (5), input2 (5), input1 (5), after (5), local (5), element (5), foo (5), runtime (5), declares (5), promise (5), structured (5), implementations (5), statements (5), open (5), navigator (5), you (4), foundation (4), simple (4), pdf (4), wikidata (4), special (4), changes (4), main (4), sister (4), uses (4), mode (4), edge (4), opera (4), active (4), cookies (4), http (4), ajax (4), john (4), douglas (4), crockford (4), toolkit (4), asm (4), model (4), does (4), starch (4), flanagan (4), guide (4), documents (4), types (4), rowhammer (4), functionality (4), part (4), 2005 (4), 2006 (4), execute (4), files (4), 1998 (4), e4x (4), mixins (4), traits (4), chain (4), october (4), 1996 (4), tc39 (4), stack (4), market (4), best (4), get (4), influenced (4), thus (4), written (4), within (4), purpose (4), between (4), scheme (4), keywords (4), described (4), outside (4), errors (4), wide (4), means (4), popular (4), ago (4), misplaced (4), bad (4), authors (4), embedded (4), csrf (4), request (4), malicious (4), however (4), where (4), third (4), following (4), values (4), age (4), counter2 (4), counter1 (4), count (4), closures (4), added (4), five_multiples (4), argument (4), hello (4), anonymous (4), queryselector (4), mynumber (4), scoped (4), block (4), examples (4), promises (4), blocking (4), message (4), before (4), delegation (4), bound (4), had (4), imperative (4), statistics (3), view (3), privacy (3), available (3), additional (3), terms (3), commons (3), english (3), wikibooks (3), file (3), what (3), help (3), current (3), navigation (3), hidden (3), search (3), failed (3), verification (3), high (3), level (3), dynamically (3), https (3), united (3), states (3), control (3), computer (3), coffeescript (3), react (3), express (3), backbone (3), commonjs (3), mosaic (3), gecko (3), gnome (3), storage (3), css (3), definition (3), jslint (3), people (3), framework (3), jquery (3), tamarin (3), package (3), devtools (3), closure (3), external (3), haverbeke (3), marijn (3), eloquent (3), definitive (3), magazine (3), jsben (3), spectre (3), aslr (3), drive (3), much (3), exploit (3), just (3), remote (3), trojan (3), 2004 (3), service (3), activex (3), blog (3), should (3), right (3), secure (3), modules (3), content (3), look (3), introduction (3), tessel (3), introducing (3), vanilla (3), 1997 (3), secret (3), hardware (3), share (3), viewed (3), did (3), standardization (3), bloomberg (3), date (3), dominant (3), binary (3), format (3), native (3), running (3), notation (3), being (3), static (3), microsystems (3), paper (3), attacks (3), included (3), allows (3), programs (3), although (3), intended (3), contain (3), bugs (3), write (3), always (3), known (3), out (3), over (3), embed (3), operations (3), sent (3), authentication (3), parameters (3), possible (3), target (3), even (3), fully (3), origin (3), executed (3), party (3), foreach (3), pair (3), appendchild (3), literals (3), calculate (3), once (3), single (3), checkint (3), isnan (3), various (3), alice (3), mymodule (3), true (3), yield (3), loops (3), generator (3), internal (3), increment (3), alert (3), args (3), variadic (3), needed (3), area (3), directly (3), usually (3), global (3), scope (3), long_example (3), unless (3), recursivelycompute (3), selects (3), attr (3), baz (3), span (3), well (3), made (3), environments (3), assigns (3), generally (3), reassigned (3), constant (3), explicitly (3), implicitly (3), xml (3), different (3), async (3), await (3), arrays (3), through (3), explicit (3), outer (3), distinction (3), during (3), constructors (3), orientation (3), initially (3), 123 (3), operand (3), casting (3), operands (3), weakly (3), originally (3), scoping (3), started (3), 2000s (3), rise (3), several (3), apis (3), led (3), early (3), became (3), growth (3), paradigm (3), statement (2), contact (2), under (2), apply (2), wikimedia (2), inc (2), edit (2), bahasa (2), беларуская (2), wikiversity (2), mediawiki (2), projects (2), download (2), print (2), upload (2), community (2), portal (2), learn (2), events (2), contents (2), talk (2), categories (2), sudoc (2), fast (2), lccn (2), curlie (2), spoken (2), default (2), namespace (2), protected (2), short (2), description (2), template (2), platform (2), index (2), php (2), france (2), authority (2), underscore (2), angular (2), comparisons (2), category (2), line (2), ibm (2), home (2), webkit (2), blink (2), midori (2), sputnik (2), coc (2), brave (2), websocket (2), protocols (2), indexeddb (2), lists (2), jshint (2), jsgi (2), jsdoc (2), resig (2), deno (2), wakanda (2), mootools (2), dojo (2), chakra (2), tracemonkey (2), spidermonkey (2), qtscript (2), javascriptcore (2), caja (2), shell (2), python (2), perl (2), ryan (2), dahl (2), assemblyscript (2), services (2), brackets (2), ide (2), editors (2), inspector (2), opa (2), livescript (2), haxe (2), dart (2), objective (2), eslint (2), analysis (2), audio (2), revision (2), minutes (2), definitions (2), 3rd (2), reilly (2), further (2), reading (2), popularity (2), performance (2), benchmark (2), ars (2), technica (2), exploits (2), anc (2), why (2), arxiv (2), horse (2), pack (2), redirected (2), frame (2), vista (2), macromedia (2), flash (2), lets (2), bug (2), paul (2), deleted (2), jan (2), serviceobjects (2), never (2), sensitive (2), click (2), protection (2), mozillazine (2), ses (2), adsafe (2), making (2), safe (2), 262 (2), archive (2), 59327 (2), 282 (2), concurrency (2), cocktailjs (2), approaches (2), herman (2), addison (2), wesley (2), 321 (2), 81218 (2), effective (2), prototypal (2), structures (2), www (2), image (2), espruino (2), useful (2), devices (2), acrobat (2), 2000 (2), increase (2), w3techs (2), legal (2), proposals (2), state (2), success (2), sams (2), wiley (2), sons (2), lifehacker (2), speed (2), games (2), test (2), beta (2), speakingjs (2), chapter (2), awk (2), youtube (2), immediate (2), publication (2), references (2), heavy (2), aid (2), subset (2), since (2), supported (2), otherwise (2), easily (2), differences (2), prominent (2), compiled (2), finally (2), appeared (2), james (2), typically (2), designed (2), sandboxed (2), stand (2), alone (2), every (2), important (2), against (2), execution (2), researchers (2), makes (2), played (2), overflows (2), limited (2), own (2), range (2), interface (2), attackers (2), plugin (2), coding (2), management (2), relied (2), cause (2), appear (2), rely (2), sample (2), found (2), least (2), remove (2), entirely (2), removed (2), his (2), caused (2), depending (2), very (2), passwords (2), extracted (2), prevent (2), fields (2), reverse (2), engineered (2), untrusted (2), tag (2), taking (2), actions (2), transferring (2), money (2), sites (2), solution (2), might (2), checking (2), forgery (2), occur (2), partial (2), those (2), database (2), design (2), banking (2), webpage (2), parties (2), potential (2), creating (2), either (2), printresult (2), sort (2), map (2), createelement (2), tostring (2), redefine (2), avoid (2), names (2), specified (2), double (2), redefinition (2), swap (2), abs (2), semicolons (2), integer (2), typeerror (2), throw (2), inner (2), allowed (2), advanced (2), dynamiccounter (2), rawcounter (2), context (2), immediately (2), invoked (2), logs (2), creates (2), mutable (2), generate_multiplier_function (2), writing (2), no_parentheses (2), parentheses (2), short_example (2), order (2), capture (2), above (2), hence (2), defining (2), recursive (2), below (2), integers (2), nan (2), queryselectorall (2), setting (2), bar (2), too (2), provided (2), forward (2), sets (2), automatically (2), concise (2), vendor (2), specific (2), handling (2), eventual (2), recently (2), combine (2), way (2), synchronous (2), associative (2), bind (2), relies (2), interact (2), feature (2), processes (2), associated (2), completion (2), queue (2), messages (2), miscellaneous (2), implicit (2), composition (2), delegative (2), addition (2), nested (2), lexical (2), rather (2), inheriting (2), inherit (2), key (2), ways (2), dot (2), duck (2), interpreted (2), unary (2), left (2), conversions (2), received (2), performing (2), concatenation (2), converted (2), joined (2), casts (2), begun (2), implemented (2), initial (2), eventually (2), variety (2), term (2), coined (2), later (2), others (2), device (2), scripted (2), acquired (2), established (2), draft (2), sparked (2), significant (2), continued (2), reaching (2), maturity (2), debuted (2), jit (2), vendors (2), meanwhile (2), communities (2), period (2), working (2), reached (2), collaborating (2), official (2), alongside (2), leading (2), interpreter (2), adoption (2), decided (2), core (2), driven (2), multi (2), months (2), jump (2), cookie, mobile, disclaimers, agree, registered, profit, organization, creative, attribution, sharealike, license, last, edited, utc, žemaitėška, tiếng, việt, vèneto, اردو, українська, ᨕᨘᨁᨗ, türkmençe, türkçe, тоҷикӣ, ไทย, tetun, తెలుగు, татарча, tatarça, taqbaylit, தமிழ், tagalog, svenska, suomi, sunda, srpskohrvatski, српскохрватски, српски, srpski, کوردی, soomaaliga, slovenščina, slovenčina, සිංහල, shqip, scots, саха, тыла, русский, română, qaraqalpaqsha, português, polski, pinayuanan, ភាសាខ្មែរ, پنجابی, oʻzbekcha, ўзбекча, ଓଡ଼ିଆ, norsk, bokmål, nordfriisk, 日本語, नेपाली, nederlands, မြန်မာဘာသာ, монгол, 閩東語, mìng, dĕ̤ng, ngṳ̄, melayu, مازِرونی, مصرى, मराठी, മലയാളം, македонски, magyar, lombard, lingua, franca, nova, lietuvių, latviešu, latina, кыргызча, kurdî, kiswahili, қазақша, ქართული, jawa, עברית, italiano, íslenska, interlingua, indonesia, hrvatski, हिन्दी, հայերեն, 한국어, 客家語, hak, ngî, galego, français, فارسی, euskara, esperanto, español, ελληνικά, eesti, deutsch, dansk, čeština, чӑвашла, català, brezhoneg, български, тарашкевіца, bân, lâm, বাংলা, تۆرکجه, azərbaycanca, asturianu, aragonés, العربية, ænglisc, afrikaans, printable, item, cite, permanent, link, recent, contribute, donate, random, read, views, namespaces, account, contributions, logged, personal, menu, nkc, j9u, gnd, bnf, bne, haudio, microformats, mismatch, pending, matches, webarchive, iso, american, inventions, title, oldid, 1127505758, faceted, subject, terminology, czech, republic, israel, germany, spain, national, vue, lodash, sails, meteor, meen, substituted, ember, angularjs, mongodb, mean, worldwideweb, winwap, vision, thunderhawk, teashark, skyfire, skweezer, netpositive, msn, kidzui, ibrowse, webexplorer, reader, hotjava, gazelle, elinks, legacy, dillo, deepfish, charon, blazer, arena, arachne, amaya, abaco, xombrero, webpositive, uzbl, symbian, steel, shiira, rekonq, qtweb, origyn, omniweb, mercury, iris, fluid, coast, bolt, arora, zac, spacetime, netcaptor, neoplanet, mediabrowser, greenbrowser, deepnet, aol, trident, timberwolf, tenfourfox, swiftweasel, swiftfox, strata, pogo, suite, minimo, microb, lotus, kylo, kazehakase, icedragon, ghostzilla, galeon, lite, classilla, camino, beonex, communicator, torch, salamweb, rockmelt, redcore, flock, beaker, discontinued, w3m, qutebrowser, netsurf, netfront, lynx, lunascape, flow, eww, cake, avant, 360, surf, roccat, konqueror, icab, dooble, dolphin, waterfox, seamonkey, pale, moon, meleon, basilisk, forks, tor, slimbrowser, piratebrowser, gnu, icecat, conkeror, yandex, whale, vivaldi, srware, sleipnir, silk, samsung, puffin, otter, maxthon, falkon, epic, dragon, citrio, blisk, avast, chromium, webrtc, ocsp, encryption, webgl, sync, bookmarks, sunspider, jsss, dhtml, scott, isaacs, swfobject, puremvc, cappuccino, wakandadb, jaxer, appjet, spry, sproutcore, qooxdoo, pyjs, mochikit, lively, kernel, ext, echo, nashorn, chakracore, jägermonkey, rhino, linear, kjs, inscript, futhark, carakan, wmlscript, dialects, generational, categorical, alphabetical, swift, smalltalk, simula, sql, rust, ruby, prolog, pascal, lua, lisp, kotlin, haskell, fortran, forth, erlang, cobol, basic, assembly, apl, algol, ada, timeline, qunit, mocha, jest, jasmine, unit, testing, webpack, bundlers, yarn, managers, webauthn, html5, cascading, style, sheets, vim, team, orion, phpstorm, light, table, codemirror, atom, cloud9, ace, doc, generators, komodo, debuggers, concepts, websharper, reason, purescript, nim, morfik, compiler, emscripten, elm, clojurescript, babel, atscript, supersets, dated, reflect, subsequent, edits, listen, documentation, resources, textbooks, wiktionary, zakas, nicholas, 1st, 120, 1593275402, principles, 472, 1593279509, 7th, sebastopol, california, frequently, asked, questions, switches, typescriptlang, benchmarking, playground, benchmarkjs, busting, nastier, vusec, slate, truly, terrifying, auerbach, goodin, dan, dram, bitflipping, attacking, pcs, jean, pharuns, alix, vice, motherboard, ingenious, hack, ever, seen, gruss, daniel, maurice, clémentine, mangard, stefan, induced, fault, 1507, 06955, rare, symantec, seeker, andersen, starr, technet, enhanced, browsing, advisory, privilege, escalation, overrides, cert, 713878, properly, validate, blogs, msdn, ie7, ieblog, fusion, securityfocus, webviewfoldericon, securitytracker, apple, arbitrary, redirect, festa, 2002, cnet, crypto, signtext, lines, breaks, collins, keith, quartz, programmer, broke, deleting, tiny, piece, lauinger, tobias, chaabane, abdelberi, arshad, sajjad, robertson, william, wilson, christo, kirda, engin, 17885720, s2cid, 891562, 14722, ndss, 23414, doi, 1811, 00918, northeastern, university, thou, shalt, depend, analysing, outdated, rehorik, put, your, kottelin, thor, anta, forget, reported, fixed, talkback, advertising, obsolete, 139, 149, angus, croll, published, fresh, peterseliger, blogpsot, talents, generalizing, 141, es5, 125, 127, katz, yehuda, understanding, 176, 178, destroyallsoftware, wat, korolev, mikhail, dev, quirks, 596, 55447, microcontrollers, w3schools, raspberry, gpio, leverage, treitter, livejournal, answering, question, develop, app, mahemoff, michael, readwrite, back, vengeance, clinick, andrew, ince, seeing, steady, particularly, asp, notices, patent, office, uspto, gov, serial, 75026640, compile, ashkenas, jeremy, branscombe, mary, moves, yearly, schedule, es16, brown, linux, union, lawton, george, theserverside, behind, publishing, sep, teach, yourself, hours, oct, professional, building, scalable, overview, wired, asks, yet, lightspeed, purdy, kevin, tests, computec, big, weber, tim, bbc, news, assault, giant, baker, loren, journal, gains, mccracken, harry, technologizer, unwelcome, champeon, steve, 2001, oreilly, fin, ceo, techvision, innovators, dickerson, gordon, washingtonindependent, enzer, larry, monmouth, evolution, game, changers, marc, andreessen, foreword, 712205m, 38888873, oclc, 97078208, 7645, 3188, bible, goodman, danny, 22m, eight, letters, jsconf, seibel, peter, concern, 9781430219484, coders, reflections, craft, nodejs, eps, ecma262, announce, newswire, announcing, convert, served, forerunner, 108, enables, critical, portions, close, runs, 107, strictly, variant, differs, annotations, describe, shares, featureset, transpiled, interoperate, 106, interchange, similarities, bytecode, human, readable, until, beginning, developed, communications, gosling, misconception, indeed, ancestor, inside, mind, particular, reserved, follows, naming, conventions, 105, highlighting, profiling, jsbench, 104, 103, profilers, scan, conformance, guidelines, debugger, evolved, announced, speculative, intel, processors, 102, demonstrated, bypass, cache, 101, 100, proof, concept, hard, launched, theoretically, viable, vector, horses, uncommon, vbscript, host, incorrectly, granting, demoted, capable, necessary, delete, granted, attempted, risks, similarly, confines, renderers, plugins, video, players, controls, enabled, exploitable, exploited, past, affected, capabilities, would, wish, overrun, gain, operating, superuser, api, bower, manage, dependencies, maintainers, keep, case, emerged, blind, releases, inversely, unpatched, wild, study, looking, 133, 000, median, lag, oldest, newest, 177, days, alexa, still, ceased, possibility, maintainer, occurred, azer, koçulu, repository, tens, thousands, break, selectively, disabled, clicking, save, validation, convenience, verifies, agreed, filters, invalid, characters, perfectly, conceal, operates, raw, obfuscation, obfuscated, recognize, clients, author, assume, determined, adversary, implications, requiring, token, response, post, hijacking, solutions, tricks, into, intend, bank, solely, requests, originating, carry, valid, login, credentials, initiating, require, field, authenticate, lasting, effects, referrer, header, mistakes, url, vulnerable, stored, correct, reflected, problem, violation, online, presented, potentially, disclosing, authorization, whenever, displaying, escaping, ensuring, trusted, subsets, greater, levels, especially, advertisements, embedding, isolation, deliver, minimize, risk, restrictions, perform, tasks, second, constrained, usernames, breaches, 168, 275, 638, displayed, window, comparative, shorthand, mapping, demonstrate, inherent, nature, createtextnode, define, generic, works, concatenate, declared, precision, issues, collide, delimited, quotes, leads, wrong, members, altered, afterwards, refers, actually, itself, destructuring, assignment, euclidean, algorithm, calculates, greatest, divisor, reassigning, appropriately, optional, newline, enough, numeric, finds, lowest, displays, multiplication, remains, exported, infinitely, recommended, utilize
Text of the page (random words):
rentheses input input 2 no_parentheses 3 returns 5 an arrow function like other function definitions can be executed in the same statement as they are created this is useful when writing libraries to avoid filling the global scope and for closures let three a b a b 1 2 const generate_multiplier_function a b isnan b b a a b const five_multiples generate_multiplier_function 5 the supplied argument seeds the expression and is retained by a five_multiples 1 returns 5 five_multiples 3 returns 15 five_multiples 4 returns 60 in javascript objects can be created as instances of a class object class example class ball constructor radius this radius radius this area math pi radius 2 classes and thus objects can contain functions known as methods show console log this radius const myball new ball 5 creates a new instance of the ball object with radius 5 myball radius object properties can usually be modified from the outside myball show using the inherited show function logs 6 in javascript objects can be instantiated directly from a function object functional example function ball radius const area math pi radius 2 const obj radius area objects are mutable and functions can be added as properties obj show console log obj radius return obj const myball ball 5 creates a new ball object with radius 5 no new keyword needed myball radius the instance property can be modified myball show using the show function logs 6 the new instance value variadic function demonstration arguments is a special variable 74 function sum let x 0 for let i 0 i arguments length i x arguments i return x sum 1 2 returns 3 sum 1 2 3 returns 6 as of es6 using the rest operator function sum args return args reduce a b a b sum 1 2 returns 3 sum 1 2 3 returns 6 immediately invoked function expressions are often used to create closures closures allow gathering properties and methods in a namespace and making some of them private let counter function let i 0 private property return public methods get function alert i set function value i value increment function alert i module counter get returns 0 counter set 6 counter increment returns 7 counter increment returns 8 generator objects in the form of generator functions provide a function which can be called exited and re entered while maintaining internal context statefulness 75 function rawcounter yield 1 yield 2 function dynamiccounter let count 0 while true it is not recommended to utilize while true loops in most cases yield count instances const counter1 rawcounter const counter2 dynamiccounter implementation counter1 next value 1 done false counter1 next value 2 done false counter1 next value undefined done true counter2 next value 1 done false counter2 next value 2 done false counter2 next value 3 done false infinitely javascript can export and import from modules 76 export example mymodule js this function remains private as it is not exported let sum a b return a b export variables export let name alice export let age 23 export named functions export function add num1 num2 return num1 num2 export class export class multiplication constructor num1 num2 this num1 num1 this num2 num2 add return sum this num1 this num2 import example import one property import add from mymodule js console log add 1 2 3 import multiple properties import name age from mymodule js console log name age alice 23 import all properties from a module import from module js console log name age alice 23 console log add 1 2 3 more advanced example this sample code displays various javascript features finds the lowest common multiple lcm of two numbers function lcmcalculator x y constructor function if isnan x y throw new typeerror non numeric arguments not allowed const checkint function x inner function if x 1 0 throw new typeerror x is not an integer return x this a checkint x semicolons are optional a newline is enough this b checkint y the prototype of object instances created by a constructor is that constructor s prototype property lcmcalculator prototype object literal constructor lcmcalculator when reassigning a prototype set the constructor property appropriately gcd function method that calculates the greatest common divisor euclidean algorithm let a math abs this a b math abs this b t if a b swap variables t b b a a t a b b a swap using destructuring assignment es6 while b 0 t b b a b a t only need to calculate gcd once so redefine this method actually not redefinition it s defined on the instance itself so that this gcd refers to this redefinition instead of lcmcalculator prototype gcd note that this leads to a wrong result if the lcmcalculator object members a and or b are altered afterwards also gcd gcd this gcd this gcd this gcd function return a return a object property names can be specified by strings delimited by double or single quotes lcm function variable names do not collide with object properties e g lcm is not this lcm not using this a this b to avoid fp precision issues let lcm this a this gcd this b only need to calculate lcm once so redefine this method this lcm function return lcm return lcm methods can also be declared using es6 syntax tostring using both es6 template literals and the operator to concatenate values return lcmcalculator a this a b this b define generic output function this implementation only works for web browsers function output x document body appendchild document createtextnode x document body appendchild document createelement br note array s map and foreach are defined in javascript 1 6 they are used here to demonstrate javascript s inherent functional nature 25 55 21 56 22 58 28 56 map function pair array literal mapping function return new lcmcalculator pair 0 pair 1 sort a b a lcm b lcm sort with this comparative function is a shorthand form of a function called arrow function foreach printresult function printresult obj output obj gcd obj gcd lcm obj lcm the following output should be displayed in the browser window lcmcalculator a 28 b 56 gcd 28 lcm 56 lcmcalculator a 21 b 56 gcd 7 lcm 168 lcmcalculator a 25 b 55 gcd 5 lcm 275 lcmcalculator a 22 b 58 gcd 2 lcm 638 security see also browser security javascript and the dom provide the potential for malicious authors to deliver scripts to run on a client computer via the web browser authors minimize this risk using two restrictions first scripts run in a sandbox in which they can only perform web related actions not general purpose programming tasks like creating files second scripts are constrained by the same origin policy scripts from one web site do not have access to information such as usernames passwords or cookies sent to another site most javascript related security bugs are breaches of either the same origin policy or the sandbox there are subsets of general javascript adsafe secure ecmascript ses that provide greater levels of security especially on code created by third parties such as advertisements 77 78 closure toolkit is another project for safe embedding and isolation of third party javascript and html 79 content security policy is the main intended method of ensuring that only trusted code is executed on a web page cross site vulnerabilities main articles cross site scripting and cross site request forgery a common javascript related security problem is cross site scripting xss a violation of the same origin policy xss vulnerabilities occur when an attacker can cause a target web site such as an online banking website to include a malicious script in the webpage presented to a victim the script in this example can then access the banking application with the privileges of the victim potentially disclosing secret information or transferring money without the victim s authorization a solution to xss vulnerabilities is to use html escaping whenever displaying untrusted data some browsers include partial protection against reflected xss attacks in which the attacker provides a url including malicious script however even users of those browsers are vulnerable to other xss attacks such as those where the malicious code is stored in a database only correct design of web applications on the server side can fully prevent xss xss vulnerabilities can also occur because of implementation mistakes by browser authors 80 another cross site vulnerability is cross site request forgery csrf in csrf code on an attacker s site tricks the victim s browser into taking actions the user did not intend at a target site like transferring money at a bank when target sites rely solely on cookies for request authentication requests originating from code on the attacker s site can carry the same valid login credentials of the initiating user in general the solution to csrf is to require an authentication value in a hidden form field and not only in the cookies to authenticate any request that might have lasting effects checking the http referrer header can also help javascript hijacking is a type of csrf attack in which a script tag on an attacker s site exploits a page on the victim s site that returns private information such as json or javascript possible solutions include requiring an authentication token in the post and get parameters for any response that returns private information misplaced trust in the client developers of client server applications must recognize that untrusted clients may be under the control of attackers the application author cannot assume that their javascript code will run as intended or at all because any secret embedded in the code could be extracted by a determined adversary some implications are web site authors cannot perfectly conceal how their javascript operates because the raw source code must be sent to the client the code can be obfuscated but obfuscation can be reverse engineered javascript form validation only provides convenience for users not security if a site verifies that the user agreed to its terms of service or filters invalid characters out of fields that should only contain numbers it must do so on the server not only the client scripts can be selectively disabled so javascript cannot be relied on to prevent operations such as right clicking on an image to save it 81 it is considered very bad practice to embed sensitive information such as passwords in javascript because it can be extracted by an attacker 82 misplaced trust in developers package management systems such as npm and bower are popular with javascript developers such systems allow a developer to easily manage their program s dependencies upon other developers program libraries developers trust that the maintainers of the libraries will keep them secure and up to date but that is not always the case a vulnerability has emerged because of this blind trust relied upon libraries can have new releases that cause bugs or vulnerabilities to appear in all programs that rely upon the libraries inversely a library can go unpatched with known vulnerabilities out in the wild in a study done looking over a sample of 133 000 websites researchers found 37 of the websites included a library with at least one known vulnerability 83 the median lag between the oldest library version used on each website and the newest available version of that library is 1 177 days in alexa and development of some libraries still in active use ceased years ago 83 another possibility is that the maintainer of a library may remove the library entirely this occurred in march 2016 when azer koçulu removed his repository from npm this caused tens of thousands of programs and websites depending upon his libraries to break 84 85 browser and plugin coding errors javascript provides an interface to a wide range of browser capabilities some of which may have flaws such as buffer overflows these flaws can allow attackers to write scripts that would run any code they wish on the user s system this code is not by any means limited to another javascript application for example a buffer overrun exploit can allow an attacker to gain access to the operating system s api with superuser privileges these flaws have affected major browsers including firefox 86 internet explorer 87 and safari 88 plugins such as video players adobe flash and the wide range of activex controls enabled by default in microsoft internet explorer may also have flaws exploitable via javascript such flaws have been exploited in the past 89 90 in windows vista microsoft has attempted to contain the risks of bugs such as buffer overflows by running the internet explorer process with limited privileges 91 google chrome similarly confines its page renderers to their own sandbox sandbox implementation errors web browsers are capable of running javascript outside the sandbox with the privileges necessary to for example create or delete files such privileges are not intended to be granted to code from the web incorrectly granting privileges to javascript from the web has played a role in vulnerabilities in both internet explorer 92 and firefox 93 in windows xp service pack 2 microsoft demoted jscript s privileges in internet explorer 94 microsoft windows allows javascript source files on a computer s hard drive to be launched as general purpose non sandboxed programs see windows script host this makes javascript like vbscript a theoretically viable vector for a trojan horse although javascript trojan horses are uncommon in practice 95 failed verification hardware vulnerabilities in 2015 a javascript based proof of concept implementation of a rowhammer attack was described in a paper by security researchers 96 97 98 99 in 2017 a javascript based attack via browser was demonstrated that could bypass aslr it s called aslr cache or anc 100 101 in 2018 the paper that announced the spectre attacks against speculative execution in intel and other processors included a javascript implementation 102 development tools important tools have evolved with the language every major web browser has built in web development tools including a javascript debugger static program analysis tools such as eslint and jslint scan javascript code for conformance to a set of standards and guidelines some browsers have built in profilers stand alone profiling libraries have also been created such as benchmark js and jsbench 103 104 many text editors have syntax highlighting support for javascript code related technologies java a common misconception is that javascript is the same as java both indeed have a c like syntax the c language being their most immediate common ancestor language they are also typically sandboxed when used inside a browser and javascript was designed with java s syntax and standard library in mind in particular all java keywords were reserved in original javascript javascript s standard library follows java s naming conventions and javascript s math and date objects are based on classes from java 1 0 105 java and javascript both first appeared in 1995 but java was developed by james gosling of sun microsystems and ja...
|
