assert-is-function-x

If isFunction(callbackfn) is false, throw a TypeError exception.

module.exports(callback) ⇒ * ⏏

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:

• TypeError Throws if callback is 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.