[ Web Proxy ]
URL:
Viewing: https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray [Back]  [Original]

Array.isArray() - JavaScript | MDN

MDN Web Docs

View in English Always switch to English

Array.isArray()

Baseline

20157

Array.isArray() Array

console.log(Array.isArray([1, 3, 5]));
// : true

console.log(Array.isArray("[]"));
// : false

console.log(Array.isArray(new Array(5)));
// : true

console.log(Array.isArray(new Int16Array([15, 33])));
// : false

js
Array.isArray(value)

value

value Array true false value TypedArray false

Array.isArray() Array in Array()

instanceof Array

  • Array.isArray() Array.prototype Array instanceof Array
  • Array.isArray() Array instanceof Array Array ID false

"Determining with absolute accuracy whether or not a JavaScript object is an array"

Array.isArray()

js
//  true 
Array.isArray([]);
Array.isArray([1]);
Array.isArray(new Array());
Array.isArray(new Array("a", "b", "c", "d"));
Array.isArray(new Array(3));
//  Array.prototype 
Array.isArray(Array.prototype);

//  false 
Array.isArray();
Array.isArray({});
Array.isArray(null);
Array.isArray(undefined);
Array.isArray(17);
Array.isArray("Array");
Array.isArray(true);
Array.isArray(false);
Array.isArray(new Uint8Array(32));
// 
// Array 
Array.isArray({ __proto__: Array.prototype });

instanceof Array.isArray()

Array Array.isArray instanceof

js
const iframe = document.createElement("iframe");
document.body.appendChild(iframe);
const xArray = window.frames[window.frames.length - 1].Array;
const arr = new xArray(1, 2, 3); // [1, 2, 3]

// 
Array.isArray(arr); // true
// arr  xArray.prototype 
// Array.prototype 
arr instanceof Array; // false

ECMAScript 2027 LanguageSpecification
# sec-array.isarray


Web Proxy Viewer  |  New URL  |  Original Page