isNonNull()

isNonNull<T>(value): value is T

Checks if a nullable value is not null.

Type guard that narrows Nullable<T> to T by excluding null.

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Type Parameters

T: T

The type of the value.

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Parameters

value: T | null

The nullable value to check.

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Returns: value is T

true if the value is not null, false otherwise.

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Since

1.0.0

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Example

function process(data: `Nullable<string>`) {
  if (isNonNull(data)) {
    // data is now typed as string
    console.log(data.toUpperCase());
  }
}

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How it works?

Type guard that checks if a value is not null.

Type Narrowing

Common Checks

Value	Result
undefined	true
0	true
''	true
false	true
null	false

vs isNonNullable

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Use Cases

Ensure value existence 📌

Strictly check that a value is not null (allows undefined). Useful when null has a specific semantic meaning different from undefined.

#ensure#existence#non-null#validation#semantic#strict

if (isNonNull(value)) {
  // value is T | undefined, but not null
}