ECMA-262.pdf

【实例截图】

【核心代码】

Contents Page
Introduction ....................................................................................................................................................... vii
1 Scope ............................................................................................................................................................. 1
2 Conformance ................................................................................................................................................ 1
3 Normative references .................................................................................................................................. 1
4 Overview ....................................................................................................................................................... 1
4.1 Web Scripting ............................................................................................................................................ 2
4.2 Language Overview .................................................................................................................................. 2
4.2.1 Objects .................................................................................................................................................... 3
4.2.2 The Strict Variant of ECMAScript ......................................................................................................... 4
4.3 Terms and definitions ............................................................................................................................... 4
5 Notational Conventions ............................................................................................................................... 7
5.1 Syntactic and Lexical Grammars............................................................................................................. 7
5.1.1 Context-Free Grammars ........................................................................................................................ 7
5.1.2 The Lexical and RegExp Grammars ..................................................................................................... 8
5.1.3 The Numeric String Grammar ............................................................................................................... 8
5.1.4 The Syntactic Grammar ......................................................................................................................... 8
5.1.5 The JSON Grammar ............................................................................................................................... 9
5.1.6 Grammar Notation .................................................................................................................................. 9
5.2 Algorithm Conventions .......................................................................................................................... 11
6 Source Text ................................................................................................................................................. 13
7 Lexical Conventions .................................................................................................................................. 13
7.1 Unicode Format-Control Characters ..................................................................................................... 14
7.2 White Space ............................................................................................................................................. 14
7.3 Line Terminators ..................................................................................................................................... 15
7.4 Comments ................................................................................................................................................ 16
7.5 Tokens ...................................................................................................................................................... 17
7.6 Identifier Names and Identifiers............................................................................................................. 17
7.6.1 Reserved Words ................................................................................................................................... 18
7.7 Punctuators ............................................................................................................................................. 19
7.8 Literals ...................................................................................................................................................... 19
7.8.1 Null Literals ........................................................................................................................................... 19
7.8.2 Boolean Literals ................................................................................................................................... 20
7.8.3 Numeric Literals ................................................................................................................................... 20
7.8.4 String Literals ....................................................................................................................................... 22
7.8.5 Regular Expression Literals ................................................................................................................ 24
7.9 Automatic Semicolon Insertion ............................................................................................................. 26
7.9.1 Rules of Automatic Semicolon Insertion ........................................................................................... 26
7.9.2 Examples of Automatic Semicolon Insertion .................................................................................... 27
8 Types ........................................................................................................................................................... 28
8.1 The Undefined Type ................................................................................................................................ 28
8.2 The Null Type ........................................................................................................................................... 28
8.3 The Boolean Type ................................................................................................................................... 28
8.4 The String Type ....................................................................................................................................... 28
8.5 The Number Type .................................................................................................................................... 29
8.6 The Object Type ...................................................................................................................................... 30
8.6.1 Property Attributes .............................................................................................................................. 30
8.6.2 Object Internal Properties and Methods ............................................................................................ 31
8.7 The Reference Specification Type ........................................................................................................ 35
ii © Ecma International 2011
8.7.1 GetValue (V) ......................................................................................................................................... 35
8.7.2 PutValue (V, W) .................................................................................................................................... 36
8.8 The List Specification Type ................................................................................................................... 36
8.9 The Completion Specification Type ..................................................................................................... 36
8.10 The Property Descriptor and Property Identifier Specification Types ........................................... 37
8.10.1 IsAccessorDescriptor ( Desc ) ........................................................................................................... 37
8.10.2 IsDataDescriptor ( Desc ) ................................................................................................................... 37
8.10.3 IsGenericDescriptor ( Desc ) ............................................................................................................. 37
8.10.4 FromPropertyDescriptor ( Desc ) ...................................................................................................... 38
8.10.5 ToPropertyDescriptor ( Obj ) ............................................................................................................. 38
8.11 The Lexical Environment and Environment Record Specification Types ...................................... 39
8.12 Algorithms for Object Internal Methods............................................................................................. 39
8.12.1 [[GetOwnProperty]] (P) ....................................................................................................................... 39
8.12.2 [[GetProperty]] (P)............................................................................................................................... 39
8.12.3 [[Get]] (P) ............................................................................................................................................. 39
8.12.4 [[CanPut]] (P) ....................................................................................................................................... 39
8.12.5 [[Put]] ( P, V, Throw ) .......................................................................................................................... 40
8.12.6 [[HasProperty]] (P) .............................................................................................................................. 40
8.12.7 [[Delete]] (P, Throw) ............................................................................................................................ 40
8.12.8 [[DefaultValue]] (hint) ......................................................................................................................... 41
8.12.9 [[DefineOwnProperty]] (P, Desc, Throw) .......................................................................................... 41
9 Type Conversion and Testing .................................................................................................................. 42
9.1 ToPrimitive .............................................................................................................................................. 43
9.2 ToBoolean ............................................................................................................................................... 43
9.3 ToNumber ................................................................................................................................................ 43
9.3.1 ToNumber Applied to the String Type ............................................................................................... 44
9.4 ToInteger ................................................................................................................................................. 46
9.5 ToInt32: (Signed 32 Bit Integer) ............................................................................................................ 47
9.6 ToUint32: (Unsigned 32 Bit Integer) ..................................................................................................... 47
9.7 ToUint16: (Unsigned 16 Bit Integer) ..................................................................................................... 47
9.8 ToString ................................................................................................................................................... 48
9.8.1 ToString Applied to the Number Type ............................................................................................... 48
9.9 ToObject .................................................................................................................................................. 49
9.10 CheckObjectCoercible ......................................................................................................................... 49
9.11 IsCallable ............................................................................................................................................... 49
9.12 The SameValue Algorithm ................................................................................................................... 50
10 Executable Code and Execution Contexts ........................................................................................... 50
10.1 Types of Executable Code ................................................................................................................... 50
10.1.1 Strict Mode Code ................................................................................................................................ 51
10.2 Lexical Environments .......................................................................................................................... 51
10.2.1 Environment Records ........................................................................................................................ 51
10.2.2 Lexical Environment Operations ....................................................................................................... 56
10.2.3 The Global Environment .................................................................................................................... 56
10.3 Execution Contexts .............................................................................................................................. 56
10.3.1 Identifier Resolution ........................................................................................................................... 57
10.4 Establishing an Execution Context .................................................................................................... 57
10.4.1 Entering Global Code ......................................................................................................................... 58
10.4.2 Entering Eval Code ............................................................................................................................. 58
10.4.3 Entering Function Code ..................................................................................................................... 58
10.5 Declaration Binding Instantiation ....................................................................................................... 59
10.6 Arguments Object ................................................................................................................................ 60
11 Expressions ............................................................................................................................................. 63
11.1 Primary Expressions ............................................................................................................................ 63
11.1.1 The this Keyword .............................................................................................................................. 63
11.1.2 Identifier Reference ............................................................................................................................ 63
11.1.3 Literal Reference ................................................................................................................................. 63
11.1.4 Array Initialiser .................................................................................................................................... 63
11.1.5 Object Initialiser .................................................................................................................................. 65
© Ecma International 2011 iii
11.1.6 The Grouping Operator ....................................................................................................................... 67
11.2 Left-Hand-Side Expressions ................................................................................................................ 67
11.2.1 Property Accessors ............................................................................................................................. 67
11.2.2 The new Operator ................................................................................................................................. 68
11.2.3 Function Calls ...................................................................................................................................... 68
11.2.4 Argument Lists .................................................................................................................................... 69
11.2.5 Function Expressions ......................................................................................................................... 69
11.3 Postfix Expressions .............................................................................................................................. 69
11.3.1 Postfix Increment Operator ................................................................................................................ 70
11.3.2 Postfix Decrement Operator ............................................................................................................... 70
11.4 Unary Operators .................................................................................................................................... 70
11.4.1 The delete Operator .......................................................................................................................... 70
11.4.2 The void Operator .............................................................................................................................. 71
11.4.3 The typeof Operator .......................................................................................................................... 71
11.4.4 Prefix Increment Operator .................................................................................................................. 71
11.4.5 Prefix Decrement Operator ................................................................................................................. 72
11.4.6 Unary Operator ................................................................................................................................. 72
11.4.7 Unary - Operator ................................................................................................................................. 72
11.4.8 Bitwise NOT Operator ( ~ ) .................................................................................................................. 72
11.4.9 Logical NOT Operator ( ! ) .................................................................................................................. 73
11.5 Multiplicative Operators ....................................................................................................................... 73
11.5.1 Applying the * Operator ..................................................................................................................... 73
11.5.2 Applying the / Operator ..................................................................................................................... 74
11.5.3 Applying the % Operator ..................................................................................................................... 74
11.6 Additive Operators ................................................................................................................................ 75
11.6.1 The Addition operator ( ) ................................................................................................................. 75
11.6.2 The Subtraction Operator ( - ) ........................................................................................................... 75
11.6.3 Applying the Additive Operators to Numbers .................................................................................. 75
11.7 Bitwise Shift Operators ........................................................................................................................ 76
11.7.1 The Left Shift Operator ( << ) .............................................................................................................. 76
11.7.2 The Signed Right Shift Operator ( >> ) .............................................................................................. 76
11.7.3 The Unsigned Right Shift Operator ( >>> ) ....................................................................................... 77
11.8 Relational Operators ............................................................................................................................. 77
11.8.1 The Less-than Operator ( < ) .............................................................................................................. 77
11.8.2 The Greater-than Operator ( > ) .......................................................................................................... 78
11.8.3 The Less-than-or-equal Operator ( <= ) ............................................................................................. 78
11.8.4 The Greater-than-or-equal Operator ( >= ) ........................................................................................ 78
11.8.5 The Abstract Relational Comparison Algorithm .............................................................................. 78
11.8.6 The instanceof operator ...................................................................................................................... 79
11.8.7 The in operator .................................................................................................................................... 79
11.9 Equality Operators ................................................................................................................................ 80
11.9.1 The Equals Operator ( == ) ................................................................................................................. 80
11.9.2 The Does-not-equals Operator ( != ) ................................................................................................. 80
11.9.3 The Abstract Equality Comparison Algorithm ................................................................................. 80
11.9.4 The Strict Equals Operator ( === ) ..................................................................................................... 81
11.9.5 The Strict Does-not-equal Operator ( !== ) ...................................................................................... 81
11.9.6 The Strict Equality Comparison Algorithm ....................................................................................... 82
11.10 Binary Bitwise Operators.................................................................................................................... 82
11.11 Binary Logical Operators.................................................................................................................... 83
11.12 Conditional Operator ( ? : ) ............................................................................................................. 84
11.13 Assignment Operators ........................................................................................................................ 84
11.13.1 Simple Assignment ( = ) ...................................................................................................................... 85
11.13.2 Compound Assignment ( op= ) .......................................................................................................... 85
11.14 Comma Operator ( , ) ....................................................................................................................... 85
12 Statements ................................................................................................................................................ 86
12.1 Block ....................................................................................................................................................... 86
12.2 Variable Statement ................................................................................................................................ 87
iv © Ecma International 2011
12.2.1 Strict Mode Restrictions .................................................................................................................... 88
12.3 Empty Statement .................................................................................................................................. 88
12.4 Expression Statement .......................................................................................................................... 89
12.5 The if Statement ................................................................................................................................. 89
12.6 Iteration Statements ............................................................................................................................. 90
12.6.1 The do-while Statement .................................................................................................................... 90
12.6.2 The while Statement ......................................................................................................................... 90
12.6.3 The for Statement .............................................................................................................................. 90
12.6.4 The for-in Statement ........................................................................................................................ 91
12.7 The continue Statement .................................................................................................................... 92
12.8 The break Statement ........................................................................................................................... 93
12.9 The return Statement ......................................................................................................................... 93
12.10 The with Statement ........................................................................................................................... 93
12.10.1 Strict Mode Restrictions .................................................................................................................... 94
12.11 The switch Statement ....................................................................................................................... 94
12.12 Labelled Statements ........................................................................................................................... 96
12.13 The throw Statement ......................................................................................................................... 96
12.14 The try Statement .............................................................................................................................. 96
12.14.1 Strict Mode Restrictions .................................................................................................................... 97
12.15 The debugger statement ................................................................................................................... 97
13 Function Definition .................................................................................................................................. 98
13.1 Strict Mode Restrictions ...................................................................................................................... 99
13.2 Creating Function Objects .................................................................................................................. 99
13.2.1 [[Call]] ................................................................................................................................................. 100
13.2.2 [[Construct]] ...................................................................................................................................... 100
13.2.3 The [[ThrowTypeError]] Function Object ....................................................................................... 100
14 Program .................................................................................................................................................. 101
14.1 Directive Prologues and the Use Strict Directive ............................................................................ 102
15 Standard Built-in ECMAScript Objects ............................................................................................... 102
15.1 The Global Object ............................................................................................................................... 103
15.1.1 Value Properties of the Global Object ............................................................................................ 103
15.1.2 Function Properties of the Global Object ...................................................................................... 104
15.1.3 URI Handling Function Properties .................................................................................................. 106
15.1.4 Constructor Properties of the Global Object ................................................................................. 110
15.1.5 Other Properties of the Global Object ............................................................................................ 111
15.2 Object Objects .................................................................................................................................... 111
15.2.1 The Object Constructor Called as a Function ............................................................................... 111
15.2.2 The Object Constructor .................................................................................................................... 112
15.2.3 Properties of the Object Constructor ............................................................................................. 112
15.2.4 Properties of the Object Prototype Object ..................................................................................... 115
15.2.5 Properties of Object Instances ........................................................................................................ 117
15.3 Function Objects ................................................................................................................................ 117
15.3.1 The Function Constructor Called as a Function ........................................................................... 117
15.3.2 The Function Constructor ................................................................................................................ 117
15.3.3 Properties of the Function Constructor ......................................................................................... 118
15.3.4 Properties of the Function Prototype Object ................................................................................. 118
15.3.5 Properties of Function Instances .................................................................................................... 121
15.4 Array Objects ...................................................................................................................................... 122
15.4.1 The Array Constructor Called as a Function ................................................................................. 122
15.4.2 The Array Constructor ..................................................................................................................... 122
15.4.3 Properties of the Array Constructor ............................................................................................... 123
15.4.4 Properties of the Array Prototype Object ....................................................................................... 123
15.4.5 Properties of Array Instances .......................................................................................................... 140
15.5 String Objects ..................................................................................................................................... 141
15.5.1 The String Constructor Called as a Function ................................................................................ 141
15.5.2 The String Constructor .................................................................................................................... 142
15.5.3 Properties of the String Constructor .............................................................................................. 142
© Ecma International 2011 v
15.5.4 Properties of the String Prototype Object ...................................................................................... 142
15.5.5 Properties of String Instances ......................................................................................................... 151
15.6 Boolean Objects .................................................................................................................................. 152
15.6.1 The Boolean Constructor Called as a Function ............................................................................. 152
15.6.2 The Boolean Constructor ................................................................................................................. 152
15.6.3 Properties of the Boolean Constructor ........................................................................................... 153
15.6.4 Properties of the Boolean Prototype Object................................................................................... 153
15.6.5 Properties of Boolean Instances ..................................................................................................... 153
15.7 Number Objects .................................................................................................................................. 154
15.7.1 The Number Constructor Called as a Function .............................................................................. 154
15.7.2 The Number Constructor .................................................................................................................. 154
15.7.3 Properties of the Number Constructor ............................................................................................ 154
15.7.4 Properties of the Number Prototype Object ................................................................................... 155
15.7.5 Properties of Number Instances ...................................................................................................... 159
15.8 The Math Object .................................................................................................................................. 159
15.8.1 Value Properties of the Math Object ................................................................................................ 159
15.8.2 Function Properties of the Math Object .......................................................................................... 160
15.9 Date Objects ........................................................................................................................................ 165
15.9.1 Overview of Date Objects and Definitions of Abstract Operators ............................................... 165
15.9.2 The Date Constructor Called as a Function.................................................................................... 170
15.9.3 The Date Constructor ........................................................................................................................ 170
15.9.4 Properties of the Date Constructor ................................................................................................. 171
15.9.5 Properties of the Date Prototype Object ......................................................................................... 172
15.9.6 Properties of Date Instances ............................................................................................................ 180
15.10 RegExp (Regular Expression) Objects ............................................................................................ 180
15.10.1 Patterns .............................................................................................................................................. 180
15.10.2 Pattern Semantics ............................................................................................................................. 182
15.10.3 The RegExp Constructor Called as a Function .............................................................................. 194
15.10.4 The RegExp Constructor .................................................................................................................. 194
15.10.5 Properties of the RegExp Constructor ............................................................................................ 195
15.10.6 Properties of the RegExp Prototype Object ................................................................................... 195
15.10.7 Properties of RegExp Instances ...................................................................................................... 197
15.11 Error Objects ...................................................................................................................................... 197
15.11.1 The Error Constructor Called as a Function................................................................................... 198
15.11.2 The Error Constructor ....................................................................................................................... 198
15.11.3 Properties of the Error Constructor ................................................................................................ 198
15.11.4 Properties of the Error Prototype Object ........................................................................................ 198
15.11.5 Properties of Error Instances ........................................................................................................... 199
15.11.6 Native Error Types Used in This Standard ..................................................................................... 199
15.11.7 NativeError Object Structure ............................................................................................................ 200
15.12 The JSON Object ............................................................................................................................... 201
15.12.1 The JSON Grammar .......................................................................................................................... 202
15.12.2 parse ( text [ , reviver ] ) .................................................................................................................... 203
15.12.3 stringify ( value [ , replacer [ , space ] ] ) ......................................................................................... 205
16 Errors ....................................................................................................................................................... 208
Annex A (informative) Grammar Summary .................................................................................................. 211
Annex B (informative) Compatibility ............................................................................................................. 231
Annex C (informative) The Strict Mode of ECMAScript .............................................................................. 235
Annex D (informative) Corrections and Clarifications in the 5 th Edition with Possible 3 rd Edition
Compatibility Impact ......................................................................................................................... 237
Annex E (informative) Additions and Changes in the 5 th Edition that Introduce Incompatibilities
with the 3 rd Edition ............................................................................................................................ 239
Annex F (informative) Technically Significant Corrections and Clarifications in the 5.1 Edition .......... 243