How to use Functions in JavaScript?

How to use Functions in JavaScript?

We are gonna take look at various ways/methods of using JavaScript Function. Functions are the fundamental part of JavaScript programming language. A function defined as the property of an object, is called a method to the object. A function designed to create new objects, is called an object constructor.

Functions are the fundamental part of JavaScript programming language. It is a block of code that is reusable, i.e. the function can be called anywhere in the code and perform the required task as many times as you need it.

In this article, we are gonna take look at various ways/methods of using JavaScript Function

  • Function statement:- In this method, we simply declared the function using the function keyword along with the name of the function. We passed the arguments (if any) in the round() bracket and the write the code what you want the function to perform when it is called or invoked inside the parenthesis {}.

In the function statement, the function gets hoisted, that is you can access or invoke the function even before it is declared.

square(4) //Output: 16

function square(a){
    console.log(a * a);


//Output : 4
  • Function expressions:- An anonymous function is created, which does not have its name and therefore we create an expression by assigning to a variable using the equal = operator.
var square = function(a){
    console.log(a * a);


//Output : 4

The square the variable is not the name of the function, it just points towards the address of the function in the memory space.

Note:- In function expression, we cannot access the function before it is declared as it will return the variable `square_` as `undefined_`

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