Array.prototype.keys()
The keys() method returns a new Array
Iterator object that contains the keys for each index in the array.
Syntax
keys()Return value
A new Array iterator object.
Examples
Key iterator doesn't ignore holes
var arr = ['a', , 'c'];
var sparseKeys = Object.keys(arr);
var denseKeys = [...arr.keys()];
console.log(sparseKeys); // ['0', '2']
console.log(denseKeys); // [0, 1, 2]
Specifications
| Specification |
|---|
| ECMAScript Language Specification (ECMAScript) # sec-array.prototype.keys |
Browser compatibility
BCD tables only load in the browser
See also
- A polyfill of
Array.prototype.keysis available incore-js Array.prototype.values()Array.prototype.entries()- Iteration protocols
- A polyfill