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Calling Functions in JavaScript

Functions are one of the most important building blocks of JavaScript. They allow us to group related code together and make it easier to reuse. In this post, we’ll learn how to call functions in JavaScript. We’ll cover three different types of functions: function declarations, function expressions, and arrow functions. By the end of this post, you’ll have a solid understanding of how to call functions in JavaScript.

Let’s get started!

Function Declarations

A function declaration is a function that is declared at the beginning of a script or within a scope. The function keyword is followed by the name of the function. The function name can be any valid identifier. Function declarations are hoisted, which means they are moved to the top of the current scope before execution. This means that you can call a function before it is declared in the script.

function multiply(a, b) {
  return a* b;

console.log(multiply(5, 6));
// expected output: 30

Function Expressions

A function expression is a anonymous function that is assigned to a variable. The function keyword is followed by an optional name. If the function has a name, it can be used to call itself recursively. Function expressions are not hoisted so you must declare the function before you can call it.

const getRectArea = function(width, height) {
  return width * height;

console.log(getRectArea(3, 4));
// expected output: 12

Arrow Functions

An arrow function is a shorthand notation for writing anonymous functions. Arrow functions do not have a name so they cannot be referenced elsewhere in your code. Arrow functions are not hoisted so you must declare the function before you can call it.

const foo = (args) =>{
   //Do Something

Calling a function as a method

In order to call a function as a method, it must be defined as a property on an object. Let’s look at some code.

obj = {
  foo: function() {

var func =;


In the above code, we have an object literal with a property named “foo”. The value of the foo property is a function. We can call the function by using the dot notation.

As you can see from the output, calling a function as a method is just like calling any other function.

There are several ways to call functions in JavaScript. Function declarations are hoisted so they can be called before they are declared in the script. Function expressions and arrow functions are not hoisted so they must be declared before they can be called. Each method has its own advantages and disadvantages so choose the one that best suits your needs. Thanks for reading!

Jorge Villegas
Jorge Villegas
Software Developer


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