Function: isString()

isString(val): val is string

Type guard to check if a value is a string.

Parameters

val

unknown

The value to check

Returns

val is string

True if the value is a string

Example

const value: unknown = 'hello world'

if (isString(value)) {
  // TypeScript knows value is a string
  console.log(value.toUpperCase()) // 'HELLO WORLD'
}