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  1. 給開發者的網頁技術文件
  2. JavaScript
  3. JavaScript 參考文件
  4. JavaScript 錯誤參考資料
  5. TypeError: "x" has no properties
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在本文中

  • 訊息
  • 錯誤類型
  • 哪裡錯了？
  • 示例
  • 參見
  1. JavaScript
  2. Tutorials
  3. Complete beginners
    1. JavaScript basics
    2. JavaScript first steps
    3. JavaScript building blocks
    4. Introducing JavaScript objects
  4. JavaScript Guide
    1. Introduction
    2. Grammar and types
    3. Control flow and error handling
    4. Loops and iteration
    5. Functions
    6. Expressions and operators
    7. Numbers and dates
    8. Text formatting
    9. Regular expressions
    10. Indexed collections
    11. Keyed collections
    12. Working with objects
    13. Using classes
    14. Using promises
    15. JavaScript typed arrays
    16. Iterators and generators
    17. Meta programming
    18. JavaScript modules
  5. Intermediate
    1. Client-side JavaScript frameworks
    2. Client-side web APIs
    3. Language overview
    4. JavaScript data structures
    5. Equality comparisons and sameness
    6. Enumerability and ownership of properties
    7. Closures
  6. Advanced
    1. Inheritance and the prototype chain
    2. Memory Management
    3. Concurrency model and Event Loop
  7. References
  8. Built-in objects
    1. 標準內建物件
    2. AggregateError
    3. Array
    4. ArrayBuffer
    5. AsyncFunction
    6. AsyncGenerator
    7. AsyncGeneratorFunction
    8. AsyncIterator
    9. Atomics
    10. BigInt
    11. BigInt64Array
    12. BigUint64Array
    13. Boolean
    14. DataView
    15. Date
    16. decodeURI()
    17. decodeURIComponent()
    18. encodeURI()
    19. encodeURIComponent()
    20. Error
    21. escape() 已棄用
    22. eval()
    23. EvalError
    24. FinalizationRegistry
    25. Float16Array
    26. Float32Array
    27. Float64Array
    28. Function
    29. Generator
    30. GeneratorFunction
    31. globalThis
    32. Infinity
    33. Int16Array
    34. Int32Array
    35. Int8Array
    36. InternalError 非標準
    37. Intl
    38. isFinite()
    39. isNaN()
    40. Iterator
    41. JSON
    42. Map
    43. Math
    44. NaN
    45. Number
    46. Object
    47. parseFloat()
    48. parseInt()
    49. Promise
    50. Proxy
    51. RangeError
    52. ReferenceError
    53. Reflect
    54. RegExp
    55. Set
    56. SharedArrayBuffer
    57. 字串
    58. Symbol
    59. SyntaxError
    60. TypedArray
    61. TypeError
    62. Uint16Array
    63. Uint32Array
    64. Uint8Array
    65. Uint8ClampedArray
    66. undefined
    67. unescape() 已棄用
    68. URIError
    69. WeakMap
    70. WeakRef
    71. WeakSet
  9. Expressions & operators
    1. 運算式與運算子
    2. 相加運算子（+）
    3. Addition assignment (+=)
    4. Assignment (=)
    5. async function expression
    6. async function* expression
    7. await
    8. Bitwise AND (&)
    9. Bitwise AND assignment (&=)
    10. Bitwise NOT (~)
    11. Bitwise OR (|)
    12. Bitwise OR assignment (|=)
    13. Bitwise XOR (^)
    14. Bitwise XOR assignment (^=)
    15. class expression
    16. Comma operator (,)
    17. 條件運算子
    18. 遞減運算子（--）
    19. 屬性的刪除
    20. 解構賦值
    21. 相除運算子（/）
    22. Division assignment (/=)
    23. Equality (==)
    24. 指數運算子（**）
    25. Exponentiation assignment (**=)
    26. function expression
    27. function* expression
    28. Greater than (>)
    29. Greater than or equal (>=)
    30. Grouping operator ( )
    31. import.meta
    32. import()
    33. in
    34. 遞增運算子（++）
    35. Inequality (!=)
    36. instanceof
    37. Left shift (<<)
    38. Left shift assignment (<<=)
    39. Less than (<)
    40. Less than or equal (<=)
    41. Logical AND (&&)
    42. Logical AND assignment (&&=)
    43. Logical NOT (!)
    44. Logical OR (||)
    45. Logical OR assignment (||=)
    46. 相乘運算子（*）
    47. Multiplication assignment (*=)
    48. 建構子函數的使用
    49. new.target
    50. null
    51. Nullish coalescing assignment (??=)
    52. Nullish coalescing operator (??)
    53. Object initializer
    54. 運算子優先序
    55. 可選串連
    56. Property accessors
    57. Remainder (%)
    58. Remainder assignment (%=)
    59. Right shift (>>)
    60. Right shift assignment (>>=)
    61. Spread syntax (...)
    62. Strict equality (===)
    63. Strict inequality (!==)
    64. 相減運算子（-）
    65. Subtraction assignment (-=)
    66. super
    67. this
    68. typeof
    69. 一元負號運算子（-）
    70. 一元正號運算子（+）
    71. Unsigned right shift (>>>)
    72. Unsigned right shift assignment (>>>=)
    73. void operator
    74. yield
    75. yield*
  10. Statements & declarations
    1. 概述
    2. async function
    3. async function*
    4. 區塊
    5. break
    6. class
    7. const
    8. continue 語法
    9. debugger
    10. do...while 語法
    11. Empty statement
    12. export
    13. Expression statement
    14. for 語法
    15. for await...of
    16. for...in
    17. for...of
    18. function
    19. function*
    20. if...else
    21. import
    22. label
    23. let
    24. return
    25. switch
    26. throw
    27. try...catch 語法
    28. var
    29. while 語法
    30. with 已棄用
  11. Functions
    1. 概述
    2. 箭頭函式
    3. 預設參數( Default parameters )
    4. getter
    5. 方法定義
    6. 其餘參數
    7. setter
    8. The arguments object
  12. Classes
    1. Classes
    2. 建構子
    3. extends
    4. Private properties
    5. Public class fields
    6. static
    7. Static initialization blocks
  13. Regular expressions
    1. 概述
    2. Backreference: \1, \2
    3. Capturing group: (...)
    4. Character class escape: \d, \D, \w, \W, \s, \S
    5. Character class: [...], [^...]
    6. Character escape: \n, \u{...}
    7. Disjunction: |
    8. Input boundary assertion: ^, $
    9. Literal character: a, b
    10. Lookahead assertion: (?=...), (?!...)
    11. Lookbehind assertion: (?<=...), (?<!...)
    12. Modifier: (?ims-ims:...)
    13. Named backreference: \k<name>
    14. Named capturing group: (?<name>...)
    15. Non-capturing group: (?:...)
    16. Quantifier: *, +, ?, {n}, {n,}, {n,m}
    17. Unicode character class escape: \p{...}, \P{...}
    18. Wildcard: .
    19. Word boundary assertion: \b, \B
  14. Errors
    1. JavaScript 錯誤參考資料
    2. AggregateError: No Promise in Promise.any was resolved
    3. Error: Permission denied to access property "x"
    4. InternalError: too much recursion
    5. RangeError: argument is not a valid code point
    6. RangeError: BigInt division by zero
    7. RangeError: BigInt negative exponent
    8. RangeError: form must be one of 'NFC', 'NFD', 'NFKC', or 'NFKD'
    9. RangeError: invalid array length
    10. RangeError: invalid date
    11. RangeError: precision is out of range
    12. RangeError: radix must be an integer
    13. RangeError: repeat count must be less than infinity
    14. RangeError: repeat count must be non-negative
    15. RangeError: x can't be converted to BigInt because it isn't an integer
    16. ReferenceError: "x" is not defined
    17. ReferenceError: assignment to undeclared variable "x"
    18. ReferenceError: can't access lexical declaration 'X' before initialization
    19. ReferenceError: deprecated caller or arguments usage
    20. ReferenceError: must call super constructor before using 'this' in derived class constructor
    21. ReferenceError: super() called twice in derived class constructor
    22. SyntaxError: 'arguments'/'eval' can't be defined or assigned to in strict mode code
    23. SyntaxError: "0"-prefixed octal literals are deprecated
    24. SyntaxError: "use strict" not allowed in function with non-simple parameters
    25. SyntaxError: "x" is a reserved identifier
    26. SyntaxError: \ at end of pattern
    27. SyntaxError: a declaration in the head of a for-of loop can't have an initializer
    28. SyntaxError: applying the 'delete' operator to an unqualified name is deprecated
    29. SyntaxError: arguments is not valid in fields
    30. SyntaxError: await is only valid in async functions, async generators and modules
    31. SyntaxError: await/yield expression can't be used in parameter
    32. SyntaxError: cannot use `??` unparenthesized within `||` and `&&` expressions
    33. SyntaxError: character class escape cannot be used in class range in regular expression
    34. SyntaxError: continue must be inside loop
    35. SyntaxError: duplicate capture group name in regular expression
    36. SyntaxError: duplicate formal argument x
    37. SyntaxError: for-in loop head declarations may not have initializers
    38. SyntaxError: function statement requires a name
    39. SyntaxError: functions cannot be labelled
    40. SyntaxError: getter and setter for private name #x should either be both static or non-static
    41. SyntaxError: getter functions must have no arguments
    42. SyntaxError: identifier starts immediately after numeric literal
    43. SyntaxError: illegal character
    44. SyntaxError: import declarations may only appear at top level of a module
    45. SyntaxError: incomplete quantifier in regular expression
    46. SyntaxError: invalid assignment left-hand side
    47. SyntaxError: invalid BigInt syntax
    48. SyntaxError: invalid capture group name in regular expression
    49. SyntaxError: invalid character in class in regular expression
    50. SyntaxError: invalid class set operation in regular expression
    51. SyntaxError: invalid decimal escape in regular expression
    52. SyntaxError: invalid identity escape in regular expression
    53. SyntaxError: invalid named capture reference in regular expression
    54. SyntaxError: invalid property name in regular expression
    55. SyntaxError: invalid range in character class
    56. SyntaxError: invalid regexp group
    57. SyntaxError: invalid regular expression flag "x"
    58. SyntaxError: invalid unicode escape in regular expression
    59. SyntaxError: JSON.parse: bad parsing
    60. SyntaxError: label not found
    61. SyntaxError: missing : after property id
    62. SyntaxError: missing ) after argument list
    63. SyntaxError: missing ) after condition
    64. SyntaxError: missing ] after element list
    65. SyntaxError: missing } after function body
    66. SyntaxError: missing } after property list
    67. SyntaxError: missing = in const declaration
    68. SyntaxError: missing formal parameter
    69. SyntaxError: missing name after . operator
    70. SyntaxError: missing variable name
    71. SyntaxError: negated character class with strings in regular expression
    72. SyntaxError: new keyword cannot be used with an optional chain
    73. SyntaxError: nothing to repeat
    74. SyntaxError: numbers out of order in {} quantifier.
    75. SyntaxError: octal escape sequences can't be used in untagged template literals or in strict mode code
    76. SyntaxError: parameter after rest parameter
    77. SyntaxError: private fields can't be deleted
    78. SyntaxError: property name __proto__ appears more than once in object literal
    79. SyntaxError: raw bracket is not allowed in regular expression with unicode flag
    80. SyntaxError: redeclaration of formal parameter "x"
    81. SyntaxError: reference to undeclared private field or method #x
    82. SyntaxError: rest parameter may not have a default
    83. SyntaxError: return not in function
    84. SyntaxError: setter functions must have one argument
    85. SyntaxError: string literal contains an unescaped line break
    86. SyntaxError: super() is only valid in derived class constructors
    87. SyntaxError: tagged template cannot be used with optional chain
    88. SyntaxError: Unexpected '#' used outside of class body
    89. SyntaxError: Unexpected token
    90. SyntaxError: unlabeled break must be inside loop or switch
    91. SyntaxError: unparenthesized unary expression can't appear on the left-hand side of '**'
    92. SyntaxError: use of super property/member accesses only valid within methods or eval code within methods
    93. SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead
    94. TypeError: 'x' is not iterable
    95. TypeError: "x" is (not) "y"
    96. TypeError: "x" is not a constructor
    97. TypeError: "x" is not a function
    98. TypeError: "x" is not a non-null object
    99. TypeError: "x" is read-only
    100. TypeError: BigInt value can't be serialized in JSON
    101. TypeError: calling a builtin X constructor without new is forbidden
    102. TypeError: can't access/set private field or method: object is not the right class
    103. TypeError: can't assign to property "x" on "y": not an object
    104. TypeError: can't convert BigInt to number
    105. TypeError: can't convert x to BigInt
    106. TypeError: can't define property "x": "obj" is not extensible
    107. TypeError: can't delete non-configurable array element
    108. TypeError: can't redefine non-configurable property "x"
    109. TypeError: can't set prototype of this object
    110. TypeError: can't set prototype: it would cause a prototype chain cycle
    111. TypeError: cannot use 'in' operator to search for 'x' in 'y'
    112. TypeError: class constructors must be invoked with 'new'
    113. TypeError: cyclic object value
    114. TypeError: derived class constructor returned invalid value x
    115. TypeError: getting private setter-only property
    116. TypeError: Initializing an object twice is an error with private fields/methods
    117. TypeError: invalid 'instanceof' operand 'x'
    118. TypeError: invalid Array.prototype.sort argument
    119. TypeError: invalid assignment to const "x"
    120. TypeError: Iterator/AsyncIterator constructor can't be used directly
    121. TypeError: matchAll/replaceAll must be called with a global RegExp
    122. TypeError: More arguments needed
    123. TypeError: "x" has no properties
    124. TypeError: property "x" is non-configurable and can't be deleted
    125. TypeError: Reduce of empty array with no initial value
    126. TypeError: setting getter-only property "x"
    127. TypeError: WeakSet key/WeakMap value 'x' must be an object or an unregistered symbol
    128. TypeError: X.prototype.y called on incompatible type
    129. URIError: malformed URI sequence
    130. Warning: -file- is being assigned a //# sourceMappingURL, but already has one
    131. Warning: unreachable code after return statement
  15. Misc
    1. JavaScript technologies overview
    2. Lexical grammar
    3. Iteration protocols
    4. Strict mode
    5. Template literals
    6. Trailing commas
    7. Deprecated features

在本文中

  • 訊息
  • 錯誤類型
  • 哪裡錯了？
  • 示例
  • 參見

TypeError: "x" has no properties

訊息

TypeError: null has no properties
TypeError: undefined has no properties

錯誤類型

TypeError.

哪裡錯了？

null 與 undefined 並沒有可訪問的屬性。

示例

js
null.foo;
// TypeError: null has no properties

undefined.bar;
// TypeError: undefined has no properties

參見

  • null
  • undefined

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