[Concept Entry] Javascript: Nullish Coalescing

content/javascript/concepts/nullish-coalescing/nullish-coalescing.md

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+---
+Title: 'Nullish Coalescing'
+Description: 'Returns the right-hand operand if the left-hand operand is null or undefined, otherwise, it returns the left-hand operand.'
+Subjects:
+  - 'Web Development'
+  - 'Computer Science'
+Tags:
+  - 'Comparison'
+  - 'Logical'
+  - 'Operators'
+CatalogContent:
+- 'introduction-to-javascript'
+- 'paths/front-end-engineer-career-path'
+---
+
+A JavaScript **nullish coalescing** (`??`) operator is a logical operator that evaluates the left-hand operand and returns it if it is not nullish (i.e., not `null` or `undefined`). Otherwise, it returns the right-hand operand.
+
+## Syntax
+
+```pseudo
+value1 ?? value2
+```
+
+- `value1`: The first operand to check if it is nullish (`null` or `undefined`).
+- `value2`: The second operand that acts as the default value, returned only if `value1` is nullish.
+
+## Example
+
+The following example demonstrates the use of the nullish coalescing operator to provide a default value when the variable is `null` or `undefined`:
+
+```js
+const age = undefined;
+const defaultAge = 18;
+
+console.log(age ?? defaultAge);
+```
+
+The above code produces the following output:
+
+```shell
+18
+```
+
+## Codebyte Example
+
+The following example uses the nullish coalescing operator (`??`) to return "Guest" as a fallback value when `name` is `null`:
+
+```codebyte/javascript
+const name = null;
+const defaultName = "Guest";
+
+console.log(name ?? defaultName);
+```