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Summary: in this tutorial, you will learn about the JavaScript Object.is() method to check if the two values are the same.

The Object.is() behaves like the === operator with two differences:

• -0 and +0
• NaN

Negative zero #

The === operator treats -0 and +0 are the same value:

let amount = +0,
    volume = -0;
console.log(volume === amount);

Output:

true

However, the Object.is() treats +0 and -0 as different values. For example:

let amount = +0,
    volume = -0;
console.log(Object.is(amount, volume));

Output

false

NaN #

The === operator considers NaN and NaN are different values. The NaN is the only number that does not equal itself. For example:

let quantity = NaN;
console.log(quantity === quantity);

Output:

false

However, Object.is() treats NaN as the same value:

let quantity = NaN;

console.log(Object.is(quantity, quantity));

Output:

true

See the following sameness comparison table for reference:

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