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Banesa Guaderrama
Banesa Guaderrama

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Defining Functions

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Defining a function

Function Declarations

There are different ways to define a function in JavaScript, but I will cover three of the most common.

Function Literal

To define a function literal, you can use a function declaration:

function hello( ) {
console.log(β€˜Hello World!’);
}

The syntax of this function starts by starting with the function keyword and is followed by the name assigned to the function, in this case β€˜hello’ followed by parenthesis and finally followed by a block of code for the function.

Function Expressions

Function expressions is another way to define a function, this is done by assigning an anonymous function to a variable:

const bye = function ( ) {
console.log(β€˜Bye World’);
};

It is called anonymous function because it does not have a name. It is just created and assigned to a variable.

But, you can also create a named function expression:

const bye = function bye( ) {
console.log(β€˜Bye World’);
};

In this case the name of the function is β€˜bye’ and it is assigned to the variable β€˜goodbye’.

Function ( ) Constructors

We can also create a function by using the Constructor Function ( ). It’s body is entered as a string:

const hi = new function (β€˜console.log(β€œHi World”);  ) ;

Although this is another way to define a function, it is not recommended because there are some problems associated with placing a string inside the function body, specially because of the different number of quotation marks in the console.log.

ES6 introduced a new way to define functions using arrow notation, named 'Arrow Function, but I will make a new blog about it.

Top comments (1)

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shaunie2fly profile image
Shaun

Nice explanation ;-).

You have a small typo in one of the code examples :-)

const goodbye = function bye( ) {
console.log(β€˜Bye World’);
};

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