Checks if a value is strictly undefined.
undefined
The value will be narrowed to undefined if the function returns true.
true
To negate — check if a value is "defined" — use isDefined.
isDefined
The value to check.
true if the value is undefined, otherwise false.
false
1.0
isDefined - Use this function to check if a value is "defined".
Checks if a value is strictly
undefined.The value will be narrowed to
undefinedif the function returnstrue.To negate — check if a value is "defined" — use
isDefined.