Security: Passing a function as a parameter in JavaScript

I am very very new to JavaScript, so please bear with me!.

I was wondering if you pass a function as a parameter to another function in JavaScript, for example (disclaimer: the code may not be 100% correct, but you should get the idea!):

function(param1, param2) {

   ....
   // Do something with param 1
   param1 += 10;
   ....

   // Param 2 is a function, so call it
   param2();

   .....
}

Is this a potential security risk, or is this a common way of programming in JavaScript?.

Thanks.

In JavaScript, functions are first class citizens. You can assign a function to a var, pass functions as arguments to other functions or return a function as a result from another function.

There are many methods in JavaScript that accept a function as an argument(also called callback functions). One such example is forEach

Array.prototype.forEach();

var elements = [42, 33, 45, 5];

elements.forEach(/*anonymous function*/function(element, index) {
// do something with element
});

elements.forEach(callback);

function callback(element, index) {
//do something with element
}