TypeScript Language Specification v1.5

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A super call invokes the constructor of the base class on the instance referenced by this. A super call is processed as a function call (section 4.12) using the construct signatures of the base class constructor function type as the initial set of candidate signatures for overload resolution. Type arguments cannot be explicitly specified in a super call. If the base class is a generic class, the type arguments used to process a super call are always those specified in the extends clause that references the base class. The type of a super call expression is Void. The JavaScript code generated for a super call is specified in section 8.6.2. 4.8.2 Super Property Access A super property access consists of the keyword super followed by a dot and an identifier. Super property accesses are used to access base class member functions from derived classes and are permitted in contexts where this (section 4.2) references a derived class instance or a derived class constructor function. Specifically: In a constructor, instance member function, instance member accessor, or instance member variable initializer where this references a derived class instance, a super property access is permitted and must specify a public instance member function of the base class. In a static member function or static member accessor where this references the constructor function object of a derived class, a super property access is permitted and must specify a public static member function of the base class. Super property accesses are not permitted in other contexts, and it is not possible to access other kinds of base class members in a super property access. Note that super property accesses are not permitted inside standard function expressions nested in the above constructs because this is of type Any in such function expressions. Super property accesses are typically used to access overridden base class member functions from derived class member functions. For an example of this, see section 8.4.2. The JavaScript code generated for a super property access is specified in section 8.6.2. 4.9 Function Expressions Function expressions are extended from JavaScript to optionally include parameter and return type annotations, and a new compact form, called arrow function expressions, is introduced. FunctionExpression: ( Modified ) function Identifier opt CallSignature { FunctionBody } AssignmentExpression: ( Modified ) … ArrowFunctionExpression 62
ArrowFunctionExpression: ArrowFormalParameters => Block ArrowFormalParameters => AssignmentExpression ArrowFormalParameters: CallSignature Identifier The terms standard function expression and arrow function expression are used to refer to the FunctionExpression and ArrowFunctionExpression forms respectively. When referring to either, the generic term function expression is used. The type of a function expression is an object type containing a single call signature with parameter and return types inferred from the function expression's signature and body. The descriptions of function declarations provided in section 6.1 apply to function expressions as well, except that function expressions do not support overloading. 4.9.1 Standard Function Expressions Standard function expressions are function expressions written with the function keyword. The type of this in a standard function expression is the Any type. Standard function expressions are transformed to JavaScript in the same manner as function declarations (see section 6.6). 4.9.2 Arrow Function Expressions <strong>TypeScript</strong> supports arrow function expressions, a new feature planned for ECMAScript 6. Arrow function expressions are a compact form of function expressions that omit the function keyword and have lexical scoping of this. An arrow function expression of the form ( ... ) => expr is exactly equivalent to ( ... ) => { return expr ; } Furthermore, arrow function expressions of the forms id => { ... } id => expr are exactly equivalent to 63
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TypeScript Language Specification V
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Table of Contents 1 Introduction ..
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4.9.1 Standard Function Expressions
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9.1 Enum Declarations .............
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1 Introduction JavaScript applicati
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1.1 Ambient Declarations An ambient
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call '$' as a function. The behavio
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function getX(p: Point) { return p.
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This TypeScript class declaration c
Page 19 and 20: Section 9 describes how programmers
Page 21 and 22: Interface definitions, like the one
Page 23 and 24: TypeScript modules provide a mechan
Page 25 and 26: 2 Basic Concepts The remainder of t
Page 27 and 28: Each enum declaration has a declara
Page 29: When an identifier is resolved as a
Page 32 and 33: which infers the type of 'x' to be
Page 34 and 35: The only possible values for the Vo
Page 36 and 37: interface Array { length: number; [
Page 38 and 39: 3.4 Union Types Union types represe
Page 40 and 41: 3.5 Type Parameters A type paramete
Page 42 and 43: 3.6 Named Types Classes, interfaces
Page 44 and 45: 3.7.1 Predefined Types The any, num
Page 46 and 47: TypeMember: PropertySignature CallS
Page 48 and 49: 3.7.8 Constructor Type Literals A c
Page 50 and 51: 3.8.2 Call Signatures A call signat
Page 52 and 53: RestParameter: ... Identifier TypeA
Page 54 and 55: IndexSignature: [ Identifier : stri
Page 56 and 57: Type aliases are referenced using t
Page 58 and 59: o o If each type in U has an appare
Page 60 and 61: o o o M is a non-specialized call o
Page 62 and 63: 3.10.5 Contextual Signature Instant
Page 64 and 65: interface List { data: T; next: Lis
Page 66 and 67: 4.3 Identifiers When an expression
Page 68 and 69: of the object literal includes a nu
Page 72 and 73: ( id ) => { ... } ( id ) => expr Th
Page 74 and 75: A dot notation property access of t
Page 76 and 77: If func is of type Any, or of an ob
Page 78 and 79: An example: signature are fixed, an
Page 80 and 81: This rule means that the call to 'f
Page 82 and 83: 4.14.4 The delete Operator The 'del
Page 84 and 85: Any Boolean Number String Other Any
Page 86 and 87: where ??= is one of the compound as
Page 88 and 89: 4.18 The Comma Operator The comma o
Page 90 and 91: function foo(x: number | string) {
Page 92 and 93: function processValue(value: number
Page 95 and 96: 5 Statements This chapter describes
Page 97 and 98: BindingProperty: Identifier Initial
Page 99 and 100: Similarly, an array destructuring d
Page 101 and 102: 5.5 Continue Statements A 'continue
Page 103 and 104: 6 Functions TypeScript extends Java
Page 105 and 106: function f(x: number) { if (x
Page 107 and 108: When the output target is ECMAScrip
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Page 112 and 113: An interface has the members specif
Page 114 and 115: interface Document { createElement(
Page 117 and 118: 8 Classes TypeScript supports class
Page 119 and 120: The following constraints must be s
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Private and protected accessibility
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interface A { x: number; f: () => v
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ConstructorOverloads: ConstructorOv
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BaseClass.apply(this, arguments); a
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Initializer expressions for instanc
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var x = A.create(); // new A() var
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MemberVariableAssignments is a sequ
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In addition, the '__extends' functi
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9 Enums An enum type is a distinct
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An identifier or property access th
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var Color; (function (Color) { Colo
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If the declaration of 'M' above had
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module A { export interface X { s:
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module outer { var local = 1; expor
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where ModuleName is the name of the
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DeclarationElement: ExportAssignmen
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that source file is considered an e
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Unlike a non-instantiated internal
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import g = require("./geometry"); v
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12.1.3 Ambient Class Declarations A
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An ExternalImportDeclaration in an
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PrimaryType: ParenthesizedType Pred
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ParameterList: RequiredParameterLis
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UnaryExpression: ( Modified ) … <
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ClassExtendsClause: extends ClassTy
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ModuleBody: ModuleElements opt Modu
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AmbientClassBodyElements: AmbientCl
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TypeScript Language Specification v1.5

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