The Object is() method

By Flavio Copes

Learn how the JavaScript Object.is() method compares two values for equality, including how it treats NaN as equal and tells 0 apart from -0, unlike ===.

This method was introduced in ES2015. It aims to help comparing values.

Usage:

Object.is(a, b)

The result is always false unless:

• a and b are the same exact object
• a and b are equal strings (strings are equal when composed by the same characters, in the same order)
• a and b are equal numbers (numbers are equal when their value is equal)
• a and b are both undefined, both null, both NaN, both true or both false

0 and -0 are different values in JavaScript, so pay attention in this special case (convert all to +0 using the + unary operator before comparing, for example).

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