isNonUndefined()

isNonUndefined<T>(value): value is T

Checks if a value is not undefined.

note

Only checks undefined, not null. Use isNonNullable to check both.

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Type Parameters

T: T

The defined type.

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Parameters

value: T | undefined

The value to check.

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Returns: value is T

true if the value is not undefined, false otherwise.

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See Also

• isNonNullable
• isUndefined

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Since

1.0.0

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Example

isNonUndefined('hello');   // => true
isNonUndefined(0);         // => true
isNonUndefined(null);      // => true (only checks undefined)
isNonUndefined(undefined); // => false

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How it works?

Type guard that checks if a value is not undefined.

Type Narrowing

Common Checks

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

vs isNonNullable

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Use Cases

Verify definition 📌

Strictly check that a value is not undefined (allows null). Useful for checking if a parameter was provided, even if it's null.

#verify#undefined#definition#parameters#optional#provided

if (isNonUndefined(param)) {
  // param was passed (could be null)
}