TypeError: "x" has no properties

Message

TypeError: Unable to get property {x} of undefined or null reference (Edge)
TypeError: null has no properties (Firefox)
TypeError: undefined has no properties (Firefox)

Error type

TypeError.

What went wrong?

Both, null and undefined, have no properties you could access.

Examples

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

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

See also

Σχετικά θέματα
  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. Details of the object model
    14. Using promises
    15. Iterators and generators
    16. Meta programming
  5. Intermediate
    1. Introducing JavaScript objects
    2. Client-side web APIs
    3. A re-introduction to JavaScript
    4. JavaScript data structures
    5. Equality comparisons and sameness
    6. Closures
  6. Advanced
    1. Inheritance and the prototype chain
    2. Strict mode
    3. JavaScript typed arrays
    4. Memory Management
    5. Concurrency model and Event Loop
  7. References:
  8. Built-in objects
    1. Array
    2. ArrayBuffer
    3. AsyncFunction
    4. Atomics
    5. BigInt
    6. Boolean
    7. DataView
    8. Date
    9. Error
    10. EvalError
    11. Float32Array
    12. Float64Array
    13. Function
    14. Generator
    15. GeneratorFunction
    16. Infinity
    17. Int16Array
    18. Int32Array
    19. Int8Array
    20. InternalError
    21. Intl
    22. Intl.Collator
    23. Intl.DateTimeFormat
    24. Intl.ListFormat
    25. Intl.NumberFormat
    26. Intl.PluralRules
    27. Intl.RelativeTimeFormat
    28. JSON
    29. Map
    30. Math
    31. NaN
    32. Number
    33. Object
    34. Promise
    35. Proxy
    36. RangeError
    37. ReferenceError
    38. Reflect
    39. RegExp
    40. Set
    41. SharedArrayBuffer
    42. String
    43. Symbol
    44. SyntaxError
    45. TypeError
    46. TypedArray
    47. URIError
    48. Uint16Array
    49. Uint32Array
    50. Uint8Array
    51. Uint8ClampedArray
    52. WeakMap
    53. WeakSet
    54. WebAssembly
    55. decodeURI()
    56. decodeURIComponent()
    57. encodeURI()
    58. encodeURIComponent()
    59. escape()
    60. eval()
    61. isFinite()
    62. isNaN()
    63. null
    64. parseFloat()
    65. parseInt()
    66. undefined
    67. unescape()
    68. uneval()
  9. Expressions & operators
    1. Arithmetic operators
    2. Array comprehensions
    3. Assignment operators
    4. Bitwise operators
    5. Comma operator
    6. Comparison operators
    7. Conditional (ternary) operator
    8. Destructuring assignment
    9. Expression closures
    10. Generator comprehensions
    11. Grouping operator
    12. Legacy generator function expression
    13. Logical operators
    14. Object initializer
    15. Operator precedence
    16. Pipeline operator
    17. Property accessors
    18. Spread syntax
    19. async function expression
    20. await
    21. class expression
    22. delete operator
    23. function expression
    24. function* expression
    25. in operator
    26. instanceof
    27. new operator
    28. new.target
    29. super
    30. this
    31. typeof
    32. void operator
    33. yield
    34. yield*
  10. Statements & declarations
    1. Legacy generator function
    2. async function
    3. block
    4. break
    5. class
    6. const
    7. continue
    8. debugger
    9. default
    10. do...while
    11. empty
    12. export
    13. for
    14. for await...of
    15. for each...in
    16. for...in
    17. for...of
    18. function declaration
    19. function*
    20. if...else
    21. import
    22. import.meta
    23. label
    24. let
    25. return
    26. switch
    27. throw
    28. try...catch
    29. var
    30. while
    31. with
  11. Functions
    1. Arrow functions
    2. Default parameters
    3. Method definitions
    4. Rest parameters
    5. The arguments object
    6. getter
    7. setter
  12. Classes
    1. constructor
    2. extends
    3. static
  13. Errors
    1. Error: Permission denied to access property "x"
    2. InternalError: too much recursion
    3. RangeError: argument is not a valid code point
    4. RangeError: invalid array length
    5. RangeError: invalid date
    6. RangeError: precision is out of range
    7. RangeError: radix must be an integer
    8. RangeError: repeat count must be less than infinity
    9. RangeError: repeat count must be non-negative
    10. ReferenceError: "x" is not defined
    11. ReferenceError: assignment to undeclared variable "x"
    12. ReferenceError: can't access lexical declaration`X' before initialization
    13. ReferenceError: deprecated caller or arguments usage
    14. ReferenceError: invalid assignment left-hand side
    15. ReferenceError: reference to undefined property "x"
    16. SyntaxError: "0"-prefixed octal literals and octal escape seq. are deprecated
    17. SyntaxError: "use strict" not allowed in function with non-simple parameters
    18. SyntaxError: "x" is a reserved identifier
    19. SyntaxError: JSON.parse: bad parsing
    20. SyntaxError: Malformed formal parameter
    21. SyntaxError: Unexpected token
    22. SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead
    23. SyntaxError: a declaration in the head of a for-of loop can't have an initializer
    24. SyntaxError: applying the 'delete' operator to an unqualified name is deprecated
    25. SyntaxError: for-in loop head declarations may not have initializers
    26. SyntaxError: function statement requires a name
    27. SyntaxError: identifier starts immediately after numeric literal
    28. SyntaxError: illegal character
    29. SyntaxError: invalid regular expression flag "x"
    30. SyntaxError: missing ) after argument list
    31. SyntaxError: missing ) after condition
    32. SyntaxError: missing : after property id
    33. SyntaxError: missing ; before statement
    34. SyntaxError: missing = in const declaration
    35. SyntaxError: missing ] after element list
    36. SyntaxError: missing formal parameter
    37. SyntaxError: missing name after . operator
    38. SyntaxError: missing variable name
    39. SyntaxError: missing } after function body
    40. SyntaxError: missing } after property list
    41. SyntaxError: redeclaration of formal parameter "x"
    42. SyntaxError: return not in function
    43. SyntaxError: test for equality (==) mistyped as assignment (=)?
    44. SyntaxError: unterminated string literal
    45. TypeError: "x" has no properties
    46. TypeError: "x" is (not) "y"
    47. TypeError: "x" is not a constructor
    48. TypeError: "x" is not a function
    49. TypeError: "x" is not a non-null object
    50. TypeError: "x" is read-only
    51. TypeError: 'x' is not iterable
    52. TypeError: More arguments needed
    53. TypeError: Reduce of empty array with no initial value
    54. TypeError: can't access dead object
    55. TypeError: can't access property "x" of "y"
    56. TypeError: can't define property "x": "obj" is not extensible
    57. TypeError: can't delete non-configurable array element
    58. TypeError: can't redefine non-configurable property "x"
    59. TypeError: cannot use 'in' operator to search for 'x' in 'y'
    60. TypeError: cyclic object value
    61. TypeError: invalid 'instanceof' operand 'x'
    62. TypeError: invalid Array.prototype.sort argument
    63. TypeError: invalid arguments
    64. TypeError: invalid assignment to const "x"
    65. TypeError: property "x" is non-configurable and can't be deleted
    66. TypeError: setting getter-only property "x"
    67. TypeError: variable "x" redeclares argument
    68. URIError: malformed URI sequence
    69. Warning: -file- is being assigned a //# sourceMappingURL, but already has one
    70. Warning: 08/09 is not a legal ECMA-262 octal constant
    71. Warning: Date.prototype.toLocaleFormat is deprecated
    72. Warning: JavaScript 1.6's for-each-in loops are deprecated
    73. Warning: String.x is deprecated; use String.prototype.x instead
    74. Warning: expression closures are deprecated
    75. Warning: unreachable code after return statement
    76. X.prototype.y called on incompatible type
  14. Misc
    1. JavaScript technologies overview
    2. Lexical grammar
    3. JavaScript data structures
    4. Enumerability and ownership of properties
    5. Iteration protocols
    6. Strict mode
    7. Transitioning to strict mode
    8. Template literals
    9. Deprecated features
  15. New in JavaScript
    1. ECMAScript 2015 support in Mozilla
    2. ECMAScript 5 support in Mozilla
    3. ECMAScript Next support in Mozilla
    4. Firefox JavaScript changelog
    5. New in JavaScript 1.1
    6. New in JavaScript 1.2
    7. New in JavaScript 1.3
    8. New in JavaScript 1.4
    9. New in JavaScript 1.5
    10. New in JavaScript 1.6
    11. New in JavaScript 1.7
    12. New in JavaScript 1.8
    13. New in JavaScript 1.8.1
    14. New in JavaScript 1.8.5
  16. Documentation:
  17. Useful lists
    1. All pages index
    2. Methods index
    3. Properties index
    4. Pages tagged "JavaScript"
  18. Contribute
    1. JavaScript doc status
    2. The MDN project