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Understanding Object.is()

Understanding Object.is()

A quick guide to understanding `Object.is()`

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Rehan Sattar
ยทJul 4, 2021
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The Object.is() method determines whether two values are the same or not. It returns true if the values are the same and false if not.

let's take a look at the syntax.

Object.is(firstValue, secondValue);

๐Ÿ‘‰ Here are some of the major points you have to remember while using Object.is()

  1. Object.is doesn't coerce the values as == do.
  2. It performs === on all the compared values except signed zeroes (+0 and -0) and NaNs.
  3. The === operator (and the == operator) treats the number values -0 and +0 as equal, but Object.is() consider them unequal.
  4. The === operator treats Number.NaN and NaN as not equal but Object.is consider them equal.
  5. If objects/arrays are compared then it will compare both values and the reference in memory
  6. This method is not supported by Internet Explorer yet.

Examples:

// === comparison
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

// Object comparison
const foo = { a: 1 };
const bar = { a: 1 };
Object.is(foo, foo);              // true
Object.is(foo, bar);              // false

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

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

That's it, folks! hope it was a good read for you. Thank you! โœจ

๐Ÿ‘‰ References:

The official documentation of Object.is()

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