JavaScript in Detail: From Beginner to Advanced/

...

/

Functions in JavaScript

Functions in JavaScript

Functions in greater detail to see how functions are implemented in JavaScript.

We'll cover the following...

The illustration gives an overview of how the program flow would look for a function. Let’s list the properties of a function.

Function features

A function has the following properties:

  • A list of arguments which can be anything and is optional. This is the input to the function.

  • A program block is executed on the invocation of the function.

  • An output that is returned after the function finishes executing using a return statement.

With these features in mind, let’s learn the corresponding JavaScript syntax.

Basic function syntax and semantic

We know a function can have an input, a program block where all the instructions that would be executed reside, and an output that is returned by the function. Below is an outline of a function in JavaScript.

Here, the function starts with a function token, then the name of the function. This is followed by arguments in parentheses, and concludes with a set of instructions encapsulated within the brackets including a return statement which uses the return token within the set of instructions.

Write a small function that returns the sum of two numbers passed as arguments.

Node.js
// Define function that takes the sum of two numbers
function sum(a , b){
    console.log('Taking sum in the function'); // print to see function execute
    var ans = a + b; // assign sum of a and b to ans
    return ans; // return ans as output
}

In the above code, we wrote a basic function that has two arguments, a and b, written in the parenthesis and ...