Object.is()

The Object.is() static method determines whether two values are the same value.

{{InteractiveExample("JavaScript Demo: Object.is()")}}

```js interactive-example console.log(Object.is("1", 1)); // Expected output: false

console.log(Object.is(NaN, NaN)); // Expected output: true

console.log(Object.is(-0, 0)); // Expected output: false

const obj = {}; console.log(Object.is(obj, {})); // Expected output: false

## Syntax

```js-nolint
Object.is(value1, value2)

Parameters#

• value1
• : The first value to compare.
• value2
• : The second value to compare.

Return value#

A boolean indicating whether or not the two arguments are the same value.

Description#

Object.is() determines whether two values are the same value. Two values are the same if one of the following holds:

• both {{jsxref("undefined")}}
• both null
• both true or both false
• both strings of the same length with the same characters in the same order
• both the same object (meaning both values reference the same object in memory)
• both BigInts with the same numeric value
• both symbols that reference the same symbol value
• both numbers and
• both +0
• both -0
• both {{jsxref("NaN")}}
• or both non-zero, not {{jsxref("NaN")}}, and have the same value

Object.is() is not equivalent to the == operator. The == operator applies various coercions to both sides (if they are not the same type) before testing for equality (resulting in such behavior as "" == false being true), but Object.is() doesn't coerce either value.

Object.is() is also not equivalent to the === operator. The only difference between Object.is() and === is in their treatment of signed zeros and NaN values. The === operator (and the == operator) treats the number values -0 and +0 as equal, but treats {{jsxref("NaN")}} as not equal to each other.

Examples#

Using Object.is()#

// Case 1: Evaluation result is the same as using ===
Object.is(25, 25); // true
Object.is("foo", "foo"); // true
Object.is("foo", "bar"); // false
Object.is(null, null); // true
Object.is(undefined, undefined); // true
Object.is(window, window); // true
Object.is([], []); // false
const foo = { a: 1 };
const bar = { a: 1 };
const sameFoo = foo;
Object.is(foo, foo); // true
Object.is(foo, bar); // false
Object.is(foo, sameFoo); // true

// Case 2: Signed zero
Object.is(0, -0); // false
Object.is(+0, -0); // false
Object.is(-0, -0); // true

// Case 3: NaN
Object.is(NaN, 0 / 0); // true
Object.is(NaN, Number.NaN); // true

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• Polyfill of Object.is in core-js
• es-shims polyfill of Object.is
• Equality comparisons and sameness