Function isEmptyString

isEmptyString(str: string): boolean
Returns true if the string is empty or contains only whitespace.
Parameters
- str: string
  The input string.
Returns boolean
Example
```
isEmptyString("")       // => true
isEmptyString("   ")   // => true
isEmptyString("hello") // => false
```
- Defined in string/isEmptyString/index.ts:13