mirror of
https://github.com/toss/es-toolkit.git
synced 2024-12-18 13:31:31 +03:00
2df38fe4e2
* docs: add inline code markdown
* fix: change to undefined[] annotation
* Revert "fix: change to undefined[] annotation"
This reverts commit 3b81b8fb8a.
* chore: recommit
800 B
800 B
isUndefined
Checks if the given value is undefined.
This function tests whether the provided value is strictly equal to undefined.
It returns true if the value is undefined, and false otherwise.
This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to undefined.
Signature
function isUndefined(x: unknown): x is undefined;
Parameters
x(unknown): The value to test if it isundefined.
Returns
(x is undefined): true if the value is undefined, false otherwise.
Examples
const value1 = undefined;
const value2 = null;
const value3 = 42;
console.log(isUndefined(value1)); // true
console.log(isUndefined(value2)); // false
console.log(isUndefined(value3)); // false