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Array.prototype.keys()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since julho de 2015.

Sumário

O método keys() retorna um novo Array Iterator que contém as chaves para cada index do array.

In this article

Sintaxe

arr.keys()

Exemplos

Exemplo: uso básico

js
var arr = ["a", "b", "c"]; var iterator = arr.keys(); console.log(iterator.next()); // { value: 0, done: false } console.log(iterator.next()); // { value: 1, done: false } console.log(iterator.next()); // { value: 2, done: false } console.log(iterator.next()); // { value: undefined, done: true }

Exemplo: keys iterator não ignora lacunas

js
var arr = ["a", , "c"]; var sparseKeys = Object.keys(arr); var denseKeys = [...arr.keys()]; console.log(sparseKeys); // [0, 2] console.log(denseKeys); // [0, 1, 2]

Especificações

Specification
ECMAScript® 2027 Language Specification
# sec-array.prototype.keys

Compatibilidade de Browser

Enable JavaScript to view this browser compatibility table.

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  1. Objetos Globais
  2. Array
  3. Construtor
    1. Array()
  4. Métodos estáticos
    1. Array.from()
    2. fromAsync()
    3. Array.isArray()
    4. Array.of()
  5. Propriedades estáticas
    1. [Symbol.species]
  6. Métodos de instância
    1. Array.prototype.at()
    2. Array.prototype.concat()
    3. Array.prototype.copyWithin()
    4. Array.prototype.entries()
    5. Array.prototype.every()
    6. Array.prototype.fill()
    7. Array.prototype.filter()
    8. Array.prototype.find()
    9. Array.prototype.findIndex()
    10. findLast()
    11. findLastIndex()
    12. Array.prototype.flat()
    13. Array.prototype.flatMap()
    14. Array.prototype.forEach()
    15. Array.prototype.includes()
    16. Array.prototype.indexOf()
    17. Array.prototype.join()
    18. Array.prototype.keys()
    19. Array.prototype.lastIndexOf()
    20. Array.prototype.map()
    21. Array.prototype.pop()
    22. Array.prototype.push()
    23. Array.prototype.reduce()
    24. Array.prototype.reduceRight()
    25. Array.prototype.reverse()
    26. Array.prototype.shift()
    27. Array.prototype.slice()
    28. Array.prototype.some()
    29. Array.prototype.sort()
    30. Array.prototype.splice()
    31. Array.prototype.toLocaleString()
    32. toReversed()
    33. toSorted()
    34. toSpliced()
    35. Array.prototype.toString()
    36. Array.prototype.unshift()
    37. Array.prototype.values()
    38. with()
    39. Array.prototype[@@iterator]()
  7. Propriedades de instância
    1. Array.prototype.length
    2. Array.prototype[@@unscopables]
  8. Herança
  9. Object/Function
  10. Métodos estáticos
    1. Function.prototype.apply()
    2. Function.prototype.bind()
    3. Function.prototype.call()
    4. Function.prototype.toString()
    5. [Symbol.hasInstance]()
  11. Propriedades estáticas
    1. Function.displayName
    2. Function.length
    3. Function.name
    4. prototype
    5. Function.arguments
    6. Function.caller
  12. Métodos de instância
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toString()
    10. Object.prototype.valueOf()
  13. Propriedades de instância
    1. Object.prototype.__proto__
    2. Object.prototype.constructor

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