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TypeScript 3.6
See TypeScript 3.6
Stricter Generators
More Accurate Array Spread
See More Accurate Array Spread
Improved UX Around Promises
See Improved UX Around Promises
Better Unicode Support for Identifiers
See Better Unicode Support for Identifiers
import.meta Support in SystemJS
See import.meta Support in SystemJS
get and set Accessors Are Allowed in Ambient Contexts
See get and set Accessors Are Allowed in Ambient Contexts
Ambient Classes and Functions Can Merge
See Ambient Classes and Functions Can Merge
APIs to Support --build and --incremental
See APIs to Support --build and --incremental
Semicolon-Aware Code Edits
See Semicolon-Aware Code Edits
Smarter Auto-Import Syntax
See Smarter Auto-Import Syntax
await Completions on Promises
See await Completions on Promises
New TypeScript Playground
TypeScript 3.5
See TypeScript 3.5
Speed improvements
Type-checking speed-ups
--incremental improvements
See --incremental improvements
The Omit helper type
Improved excess property checks in union types
See Improved excess property checks in union types
The --allowUmdGlobalAccess flag
See The --allowUmdGlobalAccess flag
Smarter union type checking
See Smarter union type checking
Higher order type inference from generic constructors
See Higher order type inference from generic constructors
TypeScript 3.4
See TypeScript 3.4
Faster subsequent builds with the --incremental flag
See Faster subsequent builds with the --incremental flag
Composite projects
outFile
See outFile
Higher order type inference from generic functions
See Higher order type inference from generic functions
Improvements for ReadonlyArray and readonly tuples
See Improvements for ReadonlyArray and readonly tuples
A new syntax for ReadonlyArray
See A new syntax for ReadonlyArray
readonly tuples
See readonly tuples
readonly mapped type modifiers and readonly arrays
See readonly mapped type modifiers and readonly arrays
Caveats
See Caveats
const assertions
See const assertions
Caveats
See Caveats
Type-checking for globalThis
See Type-checking for globalThis
TypeScript 3.3
See TypeScript 3.3
Improved behavior for calling union types
See Improved behavior for calling union types
Caveats
See Caveats
Incremental file watching for composite projects in --build --watch
See Incremental file watching for composite projects in --build --watch
TypeScript 3.2
See TypeScript 3.2
strictBindCallApply
Caveats
See Caveats
Generic spread expressions in object literals
See Generic spread expressions in object literals
Generic object rest variables and parameters
See Generic object rest variables and parameters
BigInt
See BigInt
Caveats
See Caveats
Non-unit types as union discriminants
See Non-unit types as union discriminants
tsconfig.json inheritance via Node.js packages
See tsconfig.json inheritance via Node.js packages
The new --showConfig flag
Object.defineProperty declarations in JavaScript
See Object.defineProperty declarations in JavaScript
TypeScript 3.1
See TypeScript 3.1
Mapped types on tuples and arrays
See Mapped types on tuples and arrays
Properties declarations on functions
See Properties declarations on functions
Version selection with typesVersions
See Version selection with typesVersions
Matching behavior
Multiple fields
See Multiple fields
TypeScript 3.0
See TypeScript 3.0
Tuples in rest parameters and spread expressions
See Tuples in rest parameters and spread expressions
Rest parameters with tuple types
See Rest parameters with tuple types
Spread expressions with tuple types
See Spread expressions with tuple types
Generic rest parameters
Example
See Example
Optional elements in tuple types
See Optional elements in tuple types
Example
See Example
Rest elements in tuple types
See Rest elements in tuple types
Example
See Example
New unknown top type
Example
See Example
Support for defaultProps in JSX
See Support for defaultProps in JSX
Caveats
See Caveats
Explicit types on defaultProps
See Explicit types on defaultProps
Changes to @types/React
/// <reference lib="..." /> reference directives
See /// <reference lib="..." /> reference directives
Example
See Example
TypeScript 2.9
See TypeScript 2.9
Support number and symbol named properties with keyof and mapped types
See Support number and symbol named properties with keyof and mapped types
Example
See Example
Example
See Example
Recommendations
See Recommendations
Generic type arguments in JSX elements
See Generic type arguments in JSX elements
Example
See Example
Generic type arguments in generic tagged templates
See Generic type arguments in generic tagged templates
Example
See Example
import types
See import types
Example
See Example
Relaxing declaration emit visiblity rules
See Relaxing declaration emit visiblity rules
Support for import.meta
Example
See Example
New --resolveJsonModule
Example
See Example
--pretty output by default
See --pretty output by default
New --declarationMap
TypeScript 2.8
See TypeScript 2.8
Conditional Types
Example
See Example
Distributive conditional types
See Distributive conditional types
Example
See Example
Example
See Example
Example
See Example
Type inference in conditional types
See Type inference in conditional types
Predefined conditional types
See Predefined conditional types
Example
See Example
Improved control over mapped type modifiers
See Improved control over mapped type modifiers
Example
See Example
Example
See Example
Example
See Example
Improved keyof with intersection types
See Improved keyof with intersection types
Example
See Example
Better handling for namespace patterns in .js files
See Better handling for namespace patterns in .js files
IIFEs as namespace declarations
See IIFEs as namespace declarations
Defaulted declarations
Prototype assignment
Nested and merged declarations
See Nested and merged declarations
Per-file JSX factories
Example
See Example
Locally scoped JSX namespaces
See Locally scoped JSX namespaces
New --emitDeclarationsOnly
See New --emitDeclarationsOnly
TypeScript 2.7
See TypeScript 2.7
Constant-named properties
Example
See Example
Example
See Example
unique symbol
See unique symbol
Example
See Example
Example
See Example
Strict Class Initialization
See Strict Class Initialization
Definite Assignment Assertions
See Definite Assignment Assertions
Fixed Length Tuples
Improved type inference for object literals
See Improved type inference for object literals
Example
See Example
Improved handling of structurally identical classes and instanceof expressions
See Improved handling of structurally identical classes and instanceof expressions
Example:
See Example:
Type guards inferred from in operator
See Type guards inferred from in operator
Example
See Example
Support for import d from "cjs" form CommonJS modules with --esModuleInterop
See Support for import d from "cjs" form CommonJS modules with --esModuleInterop
Example
See Example
Numeric separators
Example
See Example
Cleaner output in --watch mode
See Cleaner output in --watch mode
Prettier --pretty output
TypeScript 2.6
See TypeScript 2.6
Strict function types
Example
See Example
Note:
See Note:
Support for JSX Fragment Syntax
See Support for JSX Fragment Syntax
Cache tagged template objects in modules
See Cache tagged template objects in modules
Example
See Example
Localized diagnostics on the command line
See Localized diagnostics on the command line
Example
See Example
Suppress errors in .ts files using '// @ts-ignore' comments
See Suppress errors in .ts files using '// @ts-ignore' comments
Example
See Example
Faster tsc --watch
Write-only references now flagged as unused
See Write-only references now flagged as unused
Example
See Example
Example
See Example
TypeScript 2.5
See TypeScript 2.5
Optional catch clause variables
See Optional catch clause variables
Type assertion/cast syntax in checkJs/@ts-check mode
See Type assertion/cast syntax in checkJs/@ts-check mode
Deduplicated and redirected packages
See Deduplicated and redirected packages
The --preserveSymlinks compiler flag
See The --preserveSymlinks compiler flag
TypeScript 2.4
See TypeScript 2.4
Dynamic Import Expressions
See Dynamic Import Expressions
String Enums
See String Enums
Improved inference for generics
See Improved inference for generics
Return types as inference targets
See Return types as inference targets
Type parameter inference from contextual types
See Type parameter inference from contextual types
Stricter checking for generic functions
See Stricter checking for generic functions
Strict contravariance for callback parameters
See Strict contravariance for callback parameters
Weak Type Detection
TypeScript 2.3
See TypeScript 2.3
Generators and Iteration for ES5/ES3
See Generators and Iteration for ES5/ES3
Iterators
See Iterators
Generators
See Generators
New --downlevelIteration
Async Iteration
See Async Iteration
Async iterators
See Async iterators
Async Generators
See Async Generators
The for-await-of Statement
See The for-await-of Statement
Caveats
See Caveats
Generic parameter defaults
See Generic parameter defaults
Example
See Example
New --strict master option
See New --strict master option
Enhanced --init output
Errors in .js files with --checkJs
See Errors in .js files with --checkJs
TypeScript 2.2
See TypeScript 2.2
Support for Mix-in classes
See Support for Mix-in classes
First some terminology:
Putting all of the above rules together in an example:
See Putting all of the above rules together in an example:
object type
See object type
Support for new.target
Example
See Example
Better checking for null/undefined in operands of expressions
See Better checking for null/undefined in operands of expressions
Dotted property for types with string index signatures
See Dotted property for types with string index signatures
Support for spread operator on JSX element children
See Support for spread operator on JSX element children
Example
See Example
New jsx: react-native
TypeScript 2.1
See TypeScript 2.1
keyof and Lookup Types
Example
See Example
Example
See Example
Mapped Types
See Mapped Types
Partial, Readonly, Record, and Pick
See Partial, Readonly, Record, and Pick
Object Spread and Rest
Downlevel Async Functions
Example
See Example
tsconfig.json
See tsconfig.json
dramaticWelcome.ts
Support for external helpers library (tslib)
See Support for external helpers library (tslib)
Untyped imports
See Untyped imports
Example
See Example
Support for --target ES2016, --target ES2017 and --target ESNext
See Support for --target ES2016, --target ES2017 and --target ESNext
Improved any Inference
Example
See Example
Implicit any errors
Example
See Example
Better inference for literal types
See Better inference for literal types
Example
See Example
Example
See Example
Use returned values from super calls as 'this'
See Use returned values from super calls as 'this'
Example
See Example
Configuration inheritance
Example
See Example
New --alwaysStrict
TypeScript 2.0
See TypeScript 2.0
Null- and undefined-aware types
See Null- and undefined-aware types
--strictNullChecks
Example
See Example
Assigned-before-use checking
See Assigned-before-use checking
Example
See Example
Optional parameters and properties
See Optional parameters and properties
Non-null and non-undefined type guards
See Non-null and non-undefined type guards
Example
See Example
Dotted names in type guards
See Dotted names in type guards
Example
See Example
Expression operators
Type widening
See Type widening
Non-null assertion operator
See Non-null assertion operator
Compatibility
See Compatibility
Control flow based type analysis
See Control flow based type analysis
Example
See Example
Tagged union types
Example
See Example
The never type
See The never type
Read-only properties and index signatures
See Read-only properties and index signatures
Example
See Example
Specifying the type of this for functions
See Specifying the type of this for functions
this parameters in callbacks
See this parameters in callbacks
Example
See Example
--noImplicitThis
See --noImplicitThis
Glob support in tsconfig.json
See Glob support in tsconfig.json
Example
See Example
Module resolution enhancements: BaseUrl, Path mapping, rootDirs and tracing
See Module resolution enhancements: BaseUrl, Path mapping, rootDirs and tracing
Base URL
See Base URL
Example
See Example
Path mapping
See Path mapping
Example
See Example
Virtual Directories with rootDirs
See Virtual Directories with rootDirs
Example
See Example
Tracing module resolution
Shorthand ambient module declarations
See Shorthand ambient module declarations
declarations.d.ts
Wildcard character in module names
See Wildcard character in module names
Example
See Example
Example
See Example
Support for UMD module definitions
See Support for UMD module definitions
math-lib.d.ts
See math-lib.d.ts
Optional class properties
Example
See Example
Private and Protected Constructors
See Private and Protected Constructors
Example
See Example
Abstract properties and accessors
See Abstract properties and accessors
Example
See Example
Implicit index signatures
Including built-in type declarations with --lib
See Including built-in type declarations with --lib
Example
See Example
Flag unused declarations with --noUnusedParameters and --noUnusedLocals
See Flag unused declarations with --noUnusedParameters and --noUnusedLocals
Example
See Example
Module identifiers allow for .js extension
See Module identifiers allow for .js extension
Support 'target : es5' with 'module: es6'
See Support 'target : es5' with 'module: es6'
Trailing commas in function parameter and argument lists
See Trailing commas in function parameter and argument lists
Example
See Example
New --skipLibCheck
Allow duplicate identifiers across declarations
See Allow duplicate identifiers across declarations
Example
See Example
New --declarationDir
TypeScript 1.8
See TypeScript 1.8
Type parameters as constraints
See Type parameters as constraints
Example
See Example
Control flow analysis errors
See Control flow analysis errors
Unreachable code
See Unreachable code
Example
See Example
Unused labels
See Unused labels
Example
See Example
Implicit returns
See Implicit returns
Example
See Example
Case clause fall-throughs
Example
See Example
Stateless Function Components in React
See Stateless Function Components in React
Simplified props type management in React
See Simplified props type management in React
Augmenting global/module scope from modules
See Augmenting global/module scope from modules
Example
See Example
Example
See Example
String literal types
Improved union/intersection type inference
See Improved union/intersection type inference
Example
See Example
Concatenate AMD and System modules with --outFile
See Concatenate AMD and System modules with --outFile
Example
See Example
Support for default import interop with SystemJS
See Support for default import interop with SystemJS
Allow captured let/const in loops
See Allow captured let/const in loops
Example
See Example
Improved checking for for..in statements
See Improved checking for for..in statements
Example
See Example
Modules are now emitted with a "use strict"; prologue
See Modules are now emitted with a "use strict"; prologue
Including .js files with --allowJs
See Including .js files with --allowJs
Custom JSX factories using --reactNamespace
See Custom JSX factories using --reactNamespace
Example
See Example
this-based type guards
Example
See Example
Official TypeScript NuGet package
See Official TypeScript NuGet package
Prettier error messages from tsc
See Prettier error messages from tsc
Colorization of JSX code in VS 2015
See Colorization of JSX code in VS 2015
The --project (-p) flag can now take any file path
See The --project (-p) flag can now take any file path
Allow comments in tsconfig.json
See Allow comments in tsconfig.json
Support output to IPC-driven files
See Support output to IPC-driven files
Improved support for tsconfig.json in Visual Studio 2015
See Improved support for tsconfig.json in Visual Studio 2015
A couple of limitations:
TypeScript 1.7
See TypeScript 1.7
async/await support in ES6 targets (Node v4+)
See async/await support in ES6 targets (Node v4+)
Example
See Example
Support for --target ES6 with --module
See Support for --target ES6 with --module
Example
See Example
this-typing
See this-typing
ES7 exponentiation operator
See ES7 exponentiation operator
Example
See Example
Improved checking for destructuring object literal
See Improved checking for destructuring object literal
Example
See Example
Support for decorators when targeting ES3
See Support for decorators when targeting ES3
TypeScript 1.6
See TypeScript 1.6
JSX support
See JSX support
New .tsx file extension and as operator
See New .tsx file extension and as operator
Using React
See Using React
Using other JSX frameworks
See Using other JSX frameworks
Output generation
Intersection types
Example
See Example
Local type declarations
Class expressions
Extending expressions
abstract classes and methods
See abstract classes and methods
Examples
See Examples
Generic type aliases
Stricter object literal assignment checks
See Stricter object literal assignment checks
Examples
See Examples
ES6 generators
See ES6 generators
Experimental support for async functions
See Experimental support for async functions
Example
See Example
Nightly builds
See Nightly builds
Adjustments in module resolution logic
See Adjustments in module resolution logic
Merging ambient class and interface declaration
See Merging ambient class and interface declaration
User-defined type guard functions
See User-defined type guard functions
Examples
See Examples
exclude property support in tsconfig.json
See exclude property support in tsconfig.json
--init command line option
See --init command line option
TypeScript 1.5
See TypeScript 1.5
ES6 Modules
See ES6 Modules ##
Export Declarations
Re-exporting
See Re-exporting
Default Export
See Default Export
Bare Import
See Bare Import
Destructuring in declarations and assignments
See Destructuring in declarations and assignments
Declarations
See Declarations
Assignments
See Assignments
namespace keyword
let and const support
Const
See Const
Block scoped
See Block scoped
for..of support
See for..of support
Example
See Example
Decorators
See Decorators
Example
See Example
Computed properties
Support for UMD and System module output
See Support for UMD and System module output
Unicode codepoint escapes in strings
See Unicode codepoint escapes in strings
Tagged template strings in ES3/ES5
See Tagged template strings in ES3/ES5
AMD-dependency optional names
See AMD-dependency optional names
Project support through tsconfig.json
See Project support through tsconfig.json
Example
See Example
--rootDir command line option
See --rootDir command line option
--noEmitHelpers command line option
See --noEmitHelpers command line option
--newLine command line option
See --newLine command line option
--inlineSourceMap and inlineSources command line options
See --inlineSourceMap and inlineSources command line options
TypeScript 1.4
See TypeScript 1.4
Union types
See Union types
Overview
See Overview
Stricter Generics
Better Type Inference
let declarations
See let declarations
const declarations
Template strings
See Template strings
Type Guards
See Type Guards
Type Aliases
See Type Aliases
const enum (completely inlined enums)
See const enum (completely inlined enums)
-noEmitOnError commandline option
See -noEmitOnError commandline option
AMD Module names
See AMD Module names
TypeScript 1.3
See TypeScript 1.3
Protected
See Protected
Tuple types
See Tuple types
TypeScript 1.1
See TypeScript 1.1