angular.isFunction()
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.1/angular.min.js"></script>
<h1>angular.isFunction()</h1>
JavaScript
var func = function () {};
console.log(angular.isFunction(func.bin(this))); // true
console.log(angular.isFunction(() => {})); // true