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  1. 給開發者的 Web 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 and guides
  3. Beginner's tutorials
    1. Your first website: Adding interactivity
    2. Dynamic scripting with JavaScript
    3. JavaScript frameworks and libraries
  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 strings
    8. Representing dates & times
    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. Internationalization
    18. Meta programming
    19. JavaScript modules
  5. Intermediate
    1. Advanced JavaScript objects
    2. Asynchronous JavaScript
    3. Client-side web APIs
    4. Language overview
    5. JavaScript data structures
    6. Equality comparisons and sameness
    7. Enumerability and ownership of properties
    8. Closures
  6. Advanced
    1. Inheritance and the prototype chain
    2. Memory Management
  7. References
  8. Built-in objects
    1. AggregateError
    2. Array
    3. ArrayBuffer
    4. AsyncFunction
    5. AsyncGenerator
    6. AsyncGeneratorFunction
    7. AsyncIterator
    8. Atomics
    9. BigInt
    10. BigInt64Array
    11. BigUint64Array
    12. Boolean
    13. DataView
    14. Date
    15. decodeURI()
    16. decodeURIComponent()
    17. encodeURI()
    18. encodeURIComponent()
    19. Error
    20. escape() 已棄用
    21. eval()
    22. EvalError
    23. FinalizationRegistry
    24. Float16Array
    25. Float32Array
    26. Float64Array
    27. Function
    28. Generator
    29. GeneratorFunction
    30. globalThis
    31. Infinity
    32. Int16Array
    33. Int32Array
    34. Int8Array
    35. InternalError Non-standard
    36. Intl
    37. isFinite()
    38. isNaN()
    39. Iterator
    40. JSON
    41. Map
    42. Math
    43. NaN
    44. Number
    45. Object
    46. parseFloat()
    47. parseInt()
    48. Promise
    49. Proxy
    50. RangeError
    51. ReferenceError
    52. Reflect
    53. RegExp
    54. Set
    55. SharedArrayBuffer
    56. 字串
    57. Symbol
    58. SyntaxError
    59. Temporal 實驗性質
    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. 相加運算子（+）
    2. Addition assignment (+=)
    3. Assignment (=)
    4. async function expression
    5. async function* expression
    6. await
    7. Bitwise AND (&)
    8. Bitwise AND assignment (&=)
    9. Bitwise NOT (~)
    10. Bitwise OR (|)
    11. Bitwise OR assignment (|=)
    12. Bitwise XOR (^)
    13. Bitwise XOR assignment (^=)
    14. class expression
    15. Comma operator (,)
    16. 條件運算子
    17. 遞減運算子（--）
    18. 屬性的刪除
    19. 解構
    20. 相除運算子（/）
    21. Division assignment (/=)
    22. Equality (==)
    23. 指數運算子（**）
    24. Exponentiation assignment (**=)
    25. function expression
    26. function* expression
    27. Greater than (>)
    28. Greater than or equal (>=)
    29. Grouping operator ( )
    30. import.meta
      1. import.meta.resolve()
    31. import()
    32. in
    33. 遞增運算子（++）
    34. Inequality (!=)
    35. instanceof
    36. Left shift (<<)
    37. Left shift assignment (<<=)
    38. Less than (<)
    39. Less than or equal (<=)
    40. Logical AND (&&)
    41. Logical AND assignment (&&=)
    42. Logical NOT (!)
    43. Logical OR (||)
    44. Logical OR assignment (||=)
    45. 相乘運算子（*）
    46. Multiplication assignment (*=)
    47. 建構子函數的使用
    48. new.target
    49. null
    50. Nullish coalescing assignment (??=)
    51. Nullish coalescing operator (??)
    52. Object initializer
    53. 運算子優先序
    54. 可選串連
    55. Property accessors
    56. Remainder (%)
    57. Remainder assignment (%=)
    58. Right shift (>>)
    59. Right shift assignment (>>=)
    60. Spread syntax (...)
    61. Strict equality (===)
    62. Strict inequality (!==)
    63. 相減運算子（-）
    64. Subtraction assignment (-=)
    65. super
    66. this
    67. typeof
    68. 一元負號運算子（-）
    69. 一元正號運算子（+）
    70. Unsigned right shift (>>>)
    71. Unsigned right shift assignment (>>>=)
    72. void operator
    73. yield
    74. yield*
  10. Statements & declarations
    1. async function
    2. async function*
    3. 區塊
    4. break
    5. class
    6. const
    7. continue 語法
    8. debugger
    9. do...while 語法
    10. Empty statement
    11. export
    12. Expression statement
    13. for 語法
    14. for await...of
    15. for...in
    16. for...of
    17. function
    18. function*
    19. if...else
    20. import
      1. Import attributes
    21. label
    22. let
    23. return
    24. switch
    25. throw
    26. try...catch 語法
    27. var
    28. while 語法
    29. with 已棄用
  11. Functions
    1. 箭頭函式
    2. 預設參數
    3. getter
    4. 方法定義
    5. 其餘參數
    6. setter
    7. The arguments object
      1. arguments.callee 已棄用
      2. arguments.length
      3. arguments[Symbol.iterator]()
  12. Classes
    1. 建構子
    2. extends
    3. Private properties
    4. Public class fields
    5. static
    6. Static initialization blocks
  13. Regular expressions
    1. Backreference: \1, \2
    2. Capturing group: (...)
    3. Character class escape: \d, \D, \w, \W, \s, \S
    4. Character class: [...], [^...]
    5. Character escape: \n, \u{...}
    6. Disjunction: |
    7. Input boundary assertion: ^, $
    8. Literal character: a, b
    9. Lookahead assertion: (?=...), (?!...)
    10. Lookbehind assertion: (?<=...), (?<!...)
    11. Modifier: (?ims-ims:...)
    12. Named backreference: \k<name>
    13. Named capturing group: (?<name>...)
    14. Non-capturing group: (?:...)
    15. Quantifier: *, +, ?, {n}, {n,}, {n,m}
    16. Unicode character class escape: \p{...}, \P{...}
    17. Wildcard: .
    18. Word boundary assertion: \b, \B
  14. Errors
    1. AggregateError: No Promise in Promise.any was resolved
    2. Error: Permission denied to access property "x"
    3. InternalError: too much recursion
    4. RangeError: argument is not a valid code point
    5. RangeError: BigInt division by zero
    6. RangeError: BigInt negative exponent
    7. RangeError: form must be one of 'NFC', 'NFD', 'NFKC', or 'NFKD'
    8. RangeError: invalid array length
    9. RangeError: invalid date
    10. RangeError: precision is out of range
    11. RangeError: radix must be an integer
    12. RangeError: repeat count must be less than infinity
    13. RangeError: repeat count must be non-negative
    14. RangeError: x can't be converted to BigInt because it isn't an integer
    15. ReferenceError: "x" is not defined
    16. ReferenceError: assignment to undeclared variable "x"
    17. ReferenceError: can't access lexical declaration 'X' before initialization
    18. ReferenceError: must call super constructor before using 'this' in derived class constructor
    19. ReferenceError: super() called twice in derived class constructor
    20. SyntaxError: 'arguments'/'eval' can't be defined or assigned to in strict mode code
    21. SyntaxError: "0"-prefixed octal literals are deprecated
    22. SyntaxError: "use strict" not allowed in function with non-simple parameters
    23. SyntaxError: "x" is a reserved identifier
    24. SyntaxError: \ at end of pattern
    25. SyntaxError: a declaration in the head of a for-of loop can't have an initializer
    26. SyntaxError: applying the 'delete' operator to an unqualified name is deprecated
    27. SyntaxError: arguments is not valid in fields
    28. SyntaxError: await is only valid in async functions, async generators and modules
    29. SyntaxError: await/yield expression can't be used in parameter
    30. SyntaxError: cannot use `??` unparenthesized within `||` and `&&` expressions
    31. SyntaxError: character class escape cannot be used in class range in regular expression
    32. SyntaxError: continue must be inside loop
    33. SyntaxError: duplicate capture group name in regular expression
    34. SyntaxError: duplicate formal argument x
    35. SyntaxError: for-in loop head declarations may not have initializers
    36. SyntaxError: function statement requires a name
    37. SyntaxError: functions cannot be labelled
    38. SyntaxError: getter and setter for private name #x should either be both static or non-static
    39. SyntaxError: getter functions must have no arguments
    40. SyntaxError: identifier starts immediately after numeric literal
    41. SyntaxError: illegal character
    42. SyntaxError: import declarations may only appear at top level of a module
    43. SyntaxError: incomplete quantifier in regular expression
    44. SyntaxError: invalid assignment left-hand side
    45. SyntaxError: invalid BigInt syntax
    46. SyntaxError: invalid capture group name in regular expression
    47. SyntaxError: invalid character in class in regular expression
    48. SyntaxError: invalid class set operation in regular expression
    49. SyntaxError: invalid decimal escape in regular expression
    50. SyntaxError: invalid identity escape in regular expression
    51. SyntaxError: invalid named capture reference in regular expression
    52. SyntaxError: invalid property name in regular expression
    53. SyntaxError: invalid range in character class
    54. SyntaxError: invalid regexp group
    55. SyntaxError: invalid regular expression flag "x"
    56. SyntaxError: invalid unicode escape in regular expression
    57. SyntaxError: JSON.parse: bad parsing
    58. SyntaxError: label not found
    59. SyntaxError: missing : after property id
    60. SyntaxError: missing ) after argument list
    61. SyntaxError: missing ) after condition
    62. SyntaxError: missing ] after element list
    63. SyntaxError: missing } after function body
    64. SyntaxError: missing } after property list
    65. SyntaxError: missing = in const declaration
    66. SyntaxError: missing formal parameter
    67. SyntaxError: missing name after . operator
    68. SyntaxError: missing variable name
    69. SyntaxError: negated character class with strings in regular expression
    70. SyntaxError: new keyword cannot be used with an optional chain
    71. SyntaxError: nothing to repeat
    72. SyntaxError: numbers out of order in {} quantifier.
    73. SyntaxError: octal escape sequences can't be used in untagged template literals or in strict mode code
    74. SyntaxError: parameter after rest parameter
    75. SyntaxError: private fields can't be deleted
    76. SyntaxError: property name __proto__ appears more than once in object literal
    77. SyntaxError: raw bracket is not allowed in regular expression with unicode flag
    78. SyntaxError: redeclaration of formal parameter "x"
    79. SyntaxError: reference to undeclared private field or method #x
    80. SyntaxError: rest parameter may not have a default
    81. SyntaxError: return not in function
    82. SyntaxError: setter functions must have one argument
    83. SyntaxError: string literal contains an unescaped line break
    84. SyntaxError: super() is only valid in derived class constructors
    85. SyntaxError: tagged template cannot be used with optional chain
    86. SyntaxError: Unexpected '#' used outside of class body
    87. SyntaxError: Unexpected token
    88. SyntaxError: unlabeled break must be inside loop or switch
    89. SyntaxError: unparenthesized unary expression can't appear on the left-hand side of '**'
    90. SyntaxError: use of super property/member accesses only valid within methods or eval code within methods
    91. SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead
    92. TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed
    93. TypeError: 'x' is not iterable
    94. TypeError: "x" is (not) "y"
    95. TypeError: "x" is not a constructor
    96. TypeError: "x" is not a function
    97. TypeError: "x" is not a non-null object
    98. TypeError: "x" is read-only
    99. TypeError: already executing generator
    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. Execution model
    3. Lexical grammar
    4. Iteration protocols
    5. Strict mode
    6. Template literals
    7. Trailing commas
    8. 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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