TypeScript Language Specification v1.5

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class Point { public x: number; public y: number; constructor(x: number, y: number) { this.x = x; this.y = y; // Constructor body } } 8.3.2 Super Calls Super calls (section 4.8.1) are used to call the constructor of the base class. A super call consists of the keyword super followed by an argument list enclosed in parentheses. For example: class ColoredPoint extends Point { constructor(x: number, y: number, public color: string) { super(x, y); } } Constructors of classes with no extends clause may not contain super calls, whereas constructors of derived classes must contain at least one super call somewhere in their function body. Super calls are not permitted outside constructors or in local functions inside constructors. The first statement in the body of a constructor must be a super call if both of the following are true: The containing class is a derived class. The constructor declares parameter properties or the containing class declares instance member variables with initializers. In such a required super call, it is a compile-time error for argument expressions to reference this. Initialization of parameter properties and instance member variables with initializers takes place immediately at the beginning of the constructor body if the class has no base class, or immediately following the super call if the class is a derived class. 8.3.3 Automatic Constructors If a class omits a constructor declaration, an automatic constructor is provided. In a class with no extends clause, the automatic constructor has no parameters and performs no action other than executing the instance member variable initializers (section 8.4.1), if any. In a derived class, the automatic constructor has the same parameter list (and possibly overloads) as the base class constructor. The automatically provided constructor first forwards the call to the base class constructor using a call equivalent to 118
BaseClass.apply(this, arguments); and then executes the instance member variable initializers, if any. 8.4 Property Member Declarations Property member declarations can be member variable declarations, member function declarations, or member accessor declarations. PropertyMemberDeclaration: MemberVariableDeclaration MemberFunctionDeclaration MemberAccessorDeclaration Member declarations without a static modifier are called instance member declarations. Instance property member declarations declare properties in the class instance type (section 8.2.4), and must specify names that are unique among all instance property member and parameter property declarations in the containing class, with the exception that instance get and set accessor declarations may pairwise specify the same name. Member declarations with a static modifier are called static member declarations. Static property member declarations declare properties in the constructor function type (section 8.2.5), and must specify names that are unique among all static property member declarations in the containing class, with the exception that static get and set accessor declarations may pairwise specify the same name. Note that the declaration spaces of instance and static property members are separate. Thus, it is possible to have instance and static property members with the same name. Except for overrides, as described in section 8.2.3, it is an error for a derived class to declare a property member with the same name and kind (instance or static) as a base class member. Every class automatically contains a static property member named 'prototype', the type of which is an instantiation of the class type with type Any supplied as a type argument for each type parameter. It is an error to explicitly declare a static property member with the name 'prototype'. Below is an example of a class containing both instance and static property member declarations: 119
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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
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Section 9 describes how programmers
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Interface definitions, like the one
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TypeScript modules provide a mechan
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2 Basic Concepts The remainder of t
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Each enum declaration has a declara
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When an identifier is resolved as a
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which infers the type of 'x' to be
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The only possible values for the Vo
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interface Array { length: number; [
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3.4 Union Types Union types represe
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3.5 Type Parameters A type paramete
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3.6 Named Types Classes, interfaces
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3.7.1 Predefined Types The any, num
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TypeMember: PropertySignature CallS
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3.7.8 Constructor Type Literals A c
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3.8.2 Call Signatures A call signat
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RestParameter: ... Identifier TypeA
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IndexSignature: [ Identifier : stri
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Type aliases are referenced using t
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o o If each type in U has an appare
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o o o M is a non-specialized call o
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3.10.5 Contextual Signature Instant
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interface List { data: T; next: Lis
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4.3 Identifiers When an expression
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of the object literal includes a nu
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A super call invokes the constructo
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( id ) => { ... } ( id ) => expr Th
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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
Page 121 and 122: Private and protected accessibility
Page 123 and 124: interface A { x: number; f: () => v
Page 125: ConstructorOverloads: ConstructorOv
Page 129 and 130: Initializer expressions for instanc
Page 131 and 132: var x = A.create(); // new A() var
Page 133 and 134: MemberVariableAssignments is a sequ
Page 135 and 136: In addition, the '__extends' functi
Page 137 and 138: 9 Enums An enum type is a distinct
Page 139 and 140: An identifier or property access th
Page 141: var Color; (function (Color) { Colo
Page 144 and 145: If the declaration of 'M' above had
Page 146 and 147: module A { export interface X { s:
Page 148 and 149: module outer { var local = 1; expor
Page 150 and 151: where ModuleName is the name of the
Page 152 and 153: DeclarationElement: ExportAssignmen
Page 154 and 155: that source file is considered an e
Page 156 and 157: Unlike a non-instantiated internal
Page 158 and 159: import g = require("./geometry"); v
Page 160 and 161: 12.1.3 Ambient Class Declarations A
Page 162 and 163: An ExternalImportDeclaration in an
Page 164 and 165: PrimaryType: ParenthesizedType Pred
Page 166 and 167: ParameterList: RequiredParameterLis
Page 168 and 169: UnaryExpression: ( Modified ) … <
Page 170 and 171: ClassExtendsClause: extends ClassTy
Page 172 and 173: ModuleBody: ModuleElements opt Modu
Page 174 and 175: AmbientClassBodyElements: AmbientCl
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TypeScript Language Specification v1.5

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