isNonEmptyString

Checks whether a value is a primitive, non‑empty string. This helper never throws and never mutates input. It performs a strict typeof check and does not trim, coerce, or normalize the value. Whitespace and zero‑width characters count as non‑empty. String objects (for example, new String("hello")) return false.

Signature

function isNonEmptyString(value: unknown): value is string

Parameters

Name	Data type	Description
value	unknown	The value to check. Must be a primitive string with length > 0 to return true.

Returns

A boolean:

• true: If the value is a primitive string with length greater than 0.
• false: Otherwise.

Examples

isNonEmptyString("hello")            // true
isNonEmptyString(" ")                // true (whitespace counts as non-empty)
isNonEmptyString("\u200B")           // true (zero-width space counts as non-empty)
isNonEmptyString("")                 // false
isNonEmptyString(123)                // false
isNonEmptyString(null)               // false
isNonEmptyString(undefined)          // false
isNonEmptyString(new String("x"))    // false

Notes

• This helper does not trim whitespace.
• Zero‑width characters still count as non‑empty.
• Returns false for String objects (e.g., new String("x")).
• Use normalizeNonEmptyString if you need trimming and conversion.
• Use validateNonEmptyString if you need a Result<T> instead of a boolean.

Next up

isNonNegativeNumber