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  1. Tecnologia Web para desenvolvedores
  2. JavaScript
  3. Referência JavaScript
  4. Operadores
  5. import.meta
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import.meta

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since janeiro de 2020.

O objeto import.meta mostra os metadados específicos do contexto de um módulo JavaScript. Ele contém informações sobre o módulo, como a sua URL.

In this article

Sintaxe

import.meta

Descrição

A sintaxe consiste na palavra chave import, um ponto, e o identificador meta. Normalmente no lado esquerdo do ponto é o objeto na qual a propriedade de acesso é realizada is, mas aqui import não é exatamente um objeto.

O objetoimport.meta foi criado no implementação ECMAScript,com um protótipo null. O objeto é extensível, e suas propriedades são grávaveis, configuráveis, e enumeráveis.

Exemplos

Usando import.meta

Dado o modulo my-module.js

html
<script type="module" src="my-module.js"></script>

Você pode acessar essa meta informação sobre o modulo usando o objeto import.meta.

js
console.log(import.meta); // { url: "file:///home/user/my-module.js" }

Irá retornar um objeto com propriedade URL indicando a base URL do módulo. Isso vai ser o URL da qual o script obteve, por scripts external, ou a base do documento URL contendo documento, para scripts inline.

Note que isso irá incluir parâmetros query e/ou cerquilha (i.e., seguindo o ? ou #).

Por exemplo, seguindo esse HTML:

html
<script type="module"> import "./index.mjs?someURLInfo=5"; </script>

O arquivo JavaScript a seguir vai registrar o parâmetro someURLInfo:

js
// index.mjs new URL(import.meta.url).searchParams.get("someURLInfo"); // 5

O mesmo se aplica quando um arquivo importa outro:

js
// index.mjs import "./index2.mjs?someURLInfo=5"; // index2.mjs new URL(import.meta.url).searchParams.get("someURLInfo"); // 5

Note que enquanto o Node.js vai passar nos parâmetros query (ou na cerquilha) como no exemplo passsado, a partir do Node 14.1.0, a URL com parâmetro query vai dar erro quando carregar no formulário node --experimental-modules index.mjs?someURLInfo=5 (é tratado como um arquivo ao invés de uma URL nesse contexto).

Nesse arquivo específico, o argumento passado pode ser complementar para ser usado na ampla aplicação location.href (com strings query ou cerquilha adicionada depois do caminho de arquivo HTML) (ou por Node.js, através do process.argv).

Especificações

Specification
ECMAScript® 2027 Language Specification
# prod-ImportMeta

Compatibilidade com navegadores

Enable JavaScript to view this browser compatibility table.

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  1. JavaScript
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    15. Arranjos tipados em JavaScript
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  4. Intermediário
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    5. Closures
  5. Avançado
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  6. Referências
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    4. AsyncDisposableStack
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  8. Expressões e operadores
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    7. Bitwise AND (&)
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    14. class expression
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    25. Expressão de função (function expression)
    26. Expressão function*
    27. Greater than (>)
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    29. Operador de Agrupamento
    30. import.meta
      1. import.meta.resolve()
    31. import()
    32. in operator
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    34. Desigualdade (!=)
    35. instanceof
    36. Left shift (<<)
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    40. AND lógico (&&)
    41. Logical AND assignment (&&=)
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    45. Multiplication (*)
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    47. new operator
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    49. null
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    54. Encadeamento opcional
    55. Assessores de propriedade
    56. Remainder (%)
    57. Remainder assignment (%=)
    58. Right shift (>>)
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    60. Sintaxe de Espalhamento
    61. Strict equality (===)
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    63. Subtração (-)
    64. Subtraction assignment (-=)
    65. super
    66. this
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    68. Unary negation (-)
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    70. Unsigned right shift (>>>)
    71. Unsigned right shift assignment (>>>=)
    72. void operator
    73. yield
    74. yield*
  9. Afirmações e declarações
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      1. Import attributes
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  11. Classes
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  12. Expressões Regulares
    1. Backreference: \1, \2
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    16. Escape de classes de caracteres unicode: \p{...}, \P{...}
    17. Wildcard: .
    18. Word boundary assertion: \b, \B
  13. Erros
    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" não está definido
    16. ReferenceError: Atribuição à variável não declarada "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: uma declaração na cabeça de um laço for-of não pode ter um inicializador
    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: as declarações da cabeça do laço for-in podem não ter inicializadores
    36. Erro de sintaxe: declaração de função requer um nome
    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. ReferenceError: 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: flag de expressão regular inválida "x"
    56. SyntaxError: invalid unicode escape in regular expression
    57. SyntaxError: JSON.parse: bad parsing
    58. SyntaxError: label not found
    59. Erro de Sintaxe: faltando : depois da propriedade id
    60. Erro de sintaxe falta ) depois da lista de argumentos
    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: unterminated string literal
    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: atribuição inválida para 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: null/undefined 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
  14. Mais conteúdo
    1. Visão geral das Tecnologias JavaScript
    2. Execution model
    3. Gramática léxica
    4. Protocolos de iteração
    5. Strict mode - Modo estrito
    6. Template literals
    7. Trailing commas
    8. Funcionalidades depreciadas

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