Syntax Error - MDN Web Docs Glossary: Definitions Of Web-related ...

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Syntax error

An exception caused by the incorrect use of a pre-defined syntax. Syntax errors are detected while compiling or parsing source code.

For example, if you leave off a closing brace (}) when defining a JavaScript function, you trigger a syntax error. Browser development tools display JavaScript and CSS syntax errors in the console.

In this article

• See also

See also

• Syntax error on Wikipedia
• SyntaxError JavaScript object

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1. Glossary
2. 1. Abstraction
   2. Accent
   3. Accessibility
   4. Accessibility tree
   5. Accessible description
   6. Accessible name
   7. Adobe Flash
   8. Advance measure
   9. Ajax
   10. Algorithm
   11. Alignment container
   12. Alignment subject
   13. Alpha (alpha channel)
   14. ALPN
   15. API
   16. Apple Safari
   17. Application context
   18. Argument
   19. ARIA
   20. ARPA
   21. ARPANET
   22. Array
   23. ASCII
   24. Aspect ratio
   25. Asynchronous
   26. ATAG
   27. Attribute
   28. Authentication
   29. Authenticator
   30. Bandwidth
   31. Base64
   32. Baseline
       1. Baseline (compatibility)
       2. Baseline (typography)
   33. BCP 47 language tag
   34. Beacon
   35. Bézier curve
   36. bfcache
   37. BiDi
   38. BigInt
   39. Binding
   40. Bitwise flags
   41. Blink
   42. blink element (<blink> tag)
   43. Block
       1. Block (CSS)
       2. Block (scripting)
   44. Block cipher mode of operation
   45. Block-level content
   46. Boolean
       1. Boolean (JavaScript)
       2. Boolean attribute (ARIA)
       3. Boolean attribute (HTML)
   47. Bounding box
   48. Breadcrumb
   49. Brotli compression
   50. Browser
   51. Browsing context
   52. Buffer
   53. Bun
   54. Cache
   55. Cacheable
   56. CalDAV
   57. Call stack
   58. Callback function
   59. Camel case
   60. Canonical order
   61. Canvas
   62. Card sorting
   63. CardDAV
   64. Caret
   65. CDN
   66. Certificate authority
   67. Certified
   68. Challenge-response authentication
   69. Character
   70. Character encoding
   71. Character reference
   72. Character set
   73. Chrome
   74. CIA
   75. Cipher
   76. Cipher suite
   77. Ciphertext
   78. Class
   79. Client-side rendering (CSR)
   80. Closure
   81. Cloud
   82. Cloud computing
   83. CMS
   84. Code point
   85. Code splitting
   86. Code unit
   87. Codec
   88. Color space
   89. Color wheel
   90. Compile
   91. Compile time
   92. Composite operation
   93. Compression Dictionary Transport
   94. Computer programming
   95. Conditional
   96. Constant
   97. Constructor
   98. Content header
   99. Continuous integration
   100. Continuous media
   101. Control flow
   102. Cookie
   103. Copyleft
   104. CORS
   105. CORS-safelisted request header
   106. CORS-safelisted response header
   107. Crawler
   108. Credential
   109. CRLF
   110. Cross Axis
   111. Cross-site request forgery (CSRF)
   112. Cross-site scripting (XSS)
   113. CRUD
   114. Cryptanalysis
   115. Cryptography
   116. CSP
   117. CSS
   118. CSS Object Model (CSSOM)
   119. CSS pixel
   120. CSS preprocessor
   121. Cumulative Layout Shift (CLS)
   122. Data structure
   123. Database
   124. Debounce
   125. Decryption
   126. Deep copy
   127. Delta
   128. Denial of Service (DoS)
   129. Deno
   130. Descriptor (CSS)
   131. Deserialization
   132. Developer tools
   133. Device pixel
   134. Digital certificate
   135. Digital signature
   136. Distributed Denial of Service (DDoS)
   137. DMZ
   138. DNS
   139. Doctype
   140. Document directive
   141. Document environment
   142. DOM (Document Object Model)
   143. Domain
   144. Domain name
   145. Domain sharding
   146. Dominator
   147. DSL
        1. DSL (Digital Subscriber Line)
        2. DSL (Domain-Specific Language)
   148. DTLS (Datagram Transport Layer Security)
   149. DTMF (Dual-Tone Multi-Frequency signaling)
   150. Dynamic typing
   151. ECMA
   152. ECMAScript
   153. Effective connection type
   154. Element
   155. Encapsulation
   156. Encryption
   157. Endianness
   158. Engine
        1. JavaScript engine
        2. Rendering engine
   159. Entity
   160. Entity header
   161. Enumerated
   162. Escape character
   163. Event
   164. Exception
   165. EXIF
   166. Expando
   167. Extrinsic size
   168. Fallback alignment
   169. Falsy
   170. Favicon
   171. Federated identity
   172. Fetch directive
   173. Fetch metadata request header
   174. Fingerprinting
   175. Firefox OS
   176. Firewall
   177. First Contentful Paint (FCP)
   178. First CPU idle
   179. First Input Delay (FID) Deprecated
   180. First Meaningful Paint (FMP)
   181. First Paint (FP)
   182. First-class function
   183. Flex
   184. Flex container
   185. Flex item
   186. Flexbox
   187. Flow relative values
   188. Forbidden request header
   189. Forbidden response header name
   190. Fork
   191. Fragmentainer
   192. Frame rate (FPS)
   193. FTP
   194. FTU
   195. Function
   196. Fuzz testing
   197. Gamut
   198. Garbage collection
   199. Gecko
   200. General header
   201. GIF
   202. Git
   203. Global object
   204. Global scope
   205. Global variable
   206. Glyph
   207. Google Chrome
   208. GPL
   209. GPU
   210. Graceful degradation
   211. Grid
   212. Grid areas
   213. Grid Axis
   214. Grid Cell
   215. Grid Column
   216. Grid container
   217. Grid lines
   218. Grid Row
   219. Grid Tracks
   220. Guaranteed-invalid value
   221. Gutters
   222. gzip compression
   223. Hash function
   224. Hash routing
   225. Head
   226. High-level programming language
   227. HMAC
   228. Hoisting
   229. HOL blocking
   230. Host
   231. Hotlink
   232. Houdini
   233. HPKP
   234. HSTS
   235. HTML
   236. HTML color codes
   237. HTML5
   238. HTTP
   239. HTTP content
   240. HTTP header
   241. HTTP/2
   242. HTTP/3
   243. HTTPS
   244. HTTPS RR
   245. Hyperlink
   246. Hypertext
   247. IANA
   248. ICANN
   249. ICE
   250. IDE
   251. Idempotent
   252. Identifier
   253. Identity provider (IdP)
   254. IDL
   255. IETF
   256. IIFE
   257. IMAP
   258. Immutable
   259. IndexedDB
   260. Information architecture
   261. Inheritance
   262. Ink overflow
   263. Inline-level content
   264. Input method editor
   265. Inset properties
   266. Instance
   267. Interaction to Next Paint (INP)
   268. Internationalization (i18n)
   269. Internet
   270. Interpolation
   271. Intrinsic size
   272. Invariant
   273. IP Address
   274. IPv4
   275. IPv6
   276. IRC
   277. ISO
   278. ISP
   279. ITU
   280. Jank
   281. Java
   282. JavaScript
   283. Jitter
   284. JPEG
   285. JSON
   286. JSON type representation
   287. Just-In-Time Compilation (JIT)
   288. Kebab case
   289. Key
   290. Keyword
   291. Largest Contentful Paint (LCP)
   292. Latency
   293. Layout mode
   294. Layout viewport
   295. Lazy load
   296. Leading
   297. LGPL
   298. Ligature
   299. Literal
   300. Local scope
   301. Local variable
   302. Locale
   303. Localization
   304. Logical properties
   305. Long task
   306. Loop
   307. Lossless compression
   308. Lossy compression
   309. LTR (Left To Right)
   310. Main axis
   311. Main thread
   312. Markup
   313. MathML
   314. Media
        1. Media (Audio-visual presentation)
        2. Media (CSS)
   315. Media query
   316. Metadata
   317. Method
   318. Microsoft Edge
   319. Microsoft Internet Explorer
   320. Middleware
   321. MIME
   322. MIME type
   323. Minification
   324. MitM
   325. Mixin
   326. Mobile first
   327. Modem
   328. Modularity
   329. Mozilla Firefox
   330. Multi-factor authentication
   331. Mutable
   332. MVC
   333. Namespace
   334. NaN
   335. NAT
   336. Native
   337. Navigation directive
   338. Netscape Navigator
   339. Network throttling
   340. NNTP
   341. Node
        1. Node (DOM)
        2. Node (networking)
   342. Node.js
   343. Non-normative
   344. Nonce
   345. Normative
   346. Null
   347. Nullish value
   348. Number
   349. Object
   350. Object reference
   351. OOP
   352. OpenGL
   353. OpenSSL
   354. Opera browser
   355. Operand
   356. Operator
   357. Origin
   358. OTA
   359. OWASP
   360. P2P
   361. PAC
   362. Packet
   363. Page load time
   364. Page prediction
   365. Parameter
   366. Parent object
   367. Parse
   368. Parser
   369. Payload body
   370. Payload header
   371. PDF
   372. Perceived performance
   373. Percent-encoding
   374. PHP
   375. Physical properties
   376. Pixel
   377. Placeholder names
   378. Plaintext
   379. Plugin
   380. PNG
   381. Polyfill
   382. Polymorphism
   383. POP3
   384. Port
   385. Prefetch
   386. Preflight request
   387. Prerender
   388. Presto
   389. Primitive
   390. Principle of least privilege
   391. Privileged
   392. Privileged code
   393. Progressive enhancement
   394. Progressive web applications (PWAs)
   395. Promise
   396. Property
        1. Property (CSS)
        2. Property (JavaScript)
   397. Protocol
   398. Prototype
   399. Prototype-based programming
   400. Proxy server
   401. Pseudo-class
   402. Pseudo-element
   403. Pseudocode
   404. Public-key cryptography
   405. Python
   406. Quality values
   407. Quaternion
   408. QUIC
   409. RAIL
   410. Random Number Generator
   411. Raster image
   412. Rate limit
   413. RDF
   414. Reading order
   415. Real User Monitoring (RUM)
   416. Recursion
   417. Reflow
   418. Registrable domain
   419. Regular expression
   420. Relying party
   421. Render-blocking
   422. Repaint
   423. Replaced elements
   424. Replay attack
   425. Repo
   426. Reporting directive
   427. Representation header
   428. Request header
   429. Resource Timing
   430. Response header
   431. Responsive Web Design (RWD)
   432. REST
   433. RGB
   434. RIL
   435. Robots.txt
   436. Round Trip Time (RTT)
   437. Router
   438. RSS
   439. Rsync
   440. RTCP (RTP Control Protocol)
   441. RTF
   442. RTL (Right to Left)
   443. RTP (Real-time Transport Protocol) and SRTP (Secure RTP)
   444. RTSP: Real-time streaming protocol
   445. Ruby
   446. Safe
        1. Safe (HTTP Methods)
   447. Salt
   448. Same-origin policy
   449. SCM
   450. Scope
   451. Screen reader
   452. Script-supporting element
   453. Scroll boundary
   454. Scroll chaining
   455. Scroll container
   456. Scroll snap
   457. SCTP
   458. SDK (Software Development Kit)
   459. SDP
   460. Search engine
   461. Secure context
   462. Secure Sockets Layer (SSL)
   463. Selector (CSS)
   464. Semantics
   465. SEO
   466. Serializable object
   467. Serialization
   468. Server
   469. Server Timing
   470. Server-side rendering (SSR)
   471. Session hijacking
   472. SGML
   473. Shadow tree
   474. Shallow copy
   475. Shim
   476. Signature
        1. Signature (functions)
        2. Signature (security)
   477. SIMD
   478. SISD
   479. Site
   480. Site map
   481. SLD
   482. Sloppy mode
   483. Slug
   484. Smoke test
   485. SMPTE (Society of Motion Picture and Television Engineers)
   486. SMTP
   487. Snake case
   488. Snap positions
   489. SOAP
   490. Social engineering
   491. Source map
   492. SPA (Single-page application)
   493. Specification
   494. Speculative parsing
   495. Speed index
   496. SQL
   497. SQL injection
   498. SRI
   499. Stacking context
   500. State machine
   501. Statement
   502. Static method
   503. Static site generator (SSG)
   504. Static typing
   505. Sticky activation
   506. Strict mode
   507. String
   508. Stringifier
   509. STUN
   510. Style origin
   511. Stylesheet
   512. Submit button
   513. SVG
   514. SVN
   515. Symbol
   516. Symmetric-key cryptography
   517. Synchronous
   518. Syntax
   519. Syntax error
   520. Synthetic monitoring
   521. Table grid box
   522. Table wrapper box
   523. Tag
   524. TCP
   525. TCP handshake
   526. TCP slow start
   527. Telnet
   528. Texel
   529. The Khronos Group
   530. Thread
   531. Three js
   532. Throttle
   533. Time to First Byte (TTFB)
   534. Time to Interactive (TTI)
   535. TLD
   536. TOFU
   537. Top layer
   538. Transient activation
   539. Transport Layer Security (TLS)
   540. Tree shaking
   541. Trident
   542. Truthy
   543. TTL
   544. TURN
   545. Type
   546. Type coercion
   547. Type conversion
   548. TypeScript
   549. UAAG
   550. UDP (User Datagram Protocol)
   551. UI
   552. Undefined
   553. Unicode
   554. Unix time
   555. URI
   556. URL
   557. URN
   558. Usenet
   559. User agent
   560. UTF-8
   561. UTF-16
   562. UUID
   563. UX
   564. Validator
   565. Value
   566. Variable
   567. Vendor prefix
   568. Viewport
   569. Visual viewport
   570. Void element
   571. VoIP
   572. W3C
   573. WAI
   574. WCAG
   575. Web performance
   576. Web server
   577. Web standards
   578. WebAssembly
   579. WebDAV
   580. WebExtensions
   581. WebGL
   582. WebIDL
   583. WebKit
   584. WebM
   585. WebP
   586. WebRTC
   587. WebSockets
   588. WebVTT
   589. WHATWG
   590. Whitespace
   591. WindowProxy
   592. World Wide Web
   593. Wrapper
   594. XForms Deprecated
   595. XHTML
   596. XInclude
   597. XLink
   598. XML
   599. XMLHttpRequest (XHR)
   600. XPath
   601. XQuery
   602. XSLT
   603. Zstandard compression