JavaScript Nullish Coalescing

Written by Swapnil RajaPublished 24 Aug 2026

The JavaScript nullish coalescing operator gives a fallback only when a value is null or undefined.

It is written as two question marks.

It is safer than ||, which also replaces 0, empty strings and false.

Example

javascript

const count = 0;

console.log(count ?? 10);
console.log(count || 10);

The output is 0 then 10.

|| replaced a perfectly valid zero.

What is Nullish Coalescing?

?? returns the right side only when the left is null or undefined.

PreviousJavaScript Optional Chaining NextJavaScript Getters and Setters

Complete Example

html

<!DOCTYPE html>
<html>
<head>
  <title>JavaScript Nullish Coalescing</title>
</head>
<body>

  <h1>JavaScript Nullish Coalescing</h1>

  <p id="result"></p>

  <script>
    const settings = { volume: 0 };

    const withOr = settings.volume || 50;
    const withNullish = settings.volume ?? 50;

    document.getElementById("result").innerHTML =
      "Using ||: " + withOr + "<br>Using ??: " + withNullish;
  </script>

</body>
</html>

JavaScript Nullish Coalescing

Example

What is Nullish Coalescing?

Syntax

The Problem with ||

Example

?? Keeps Real Values

Example

With Optional Chaining

Example

Cannot Mix with && or || Directly

Example

Choosing Between Them

Example

Complete Example

Try It Yourself

Important Points

Conclusion