If isFunction(callbackfn) is false, throw a TypeError exception.
Tests callback to see if it is a function, throws a TypeError if it is
not. Otherwise returns the callback.
Kind: Exported function
Returns: * - Returns callback if it is function.
Throws:
TypeErrorThrows ifcallbackis not a function.
| Param | Type | Description |
|---|---|---|
| callback | * |
The argument to be tested. |
| [message] | string |
Optional alternative message. |
Example
import assertIsFunction from 'assert-is-function-x';
const primitive = true;
const mySymbol = Symbol('mySymbol');
const symObj = Object(mySymbol);
const object = {};
const fn = function fn() {};
assertIsFunction(primitive); // TypeError 'true is not a function'.
assertIsFunction(object); // TypeError '#<Object> is not a function'.
assertIsFunction(mySymbol); // TypeError 'Symbol(mySymbol) is not a function'.
assertIsFunction(symObj); // TypeError '#<Object> is not a function'.
console.log(assertIsFunction(fn)); // Returns fn.