In JavaScript, a function is a reusable code structure that allows you to encapsulate a set of related statements in order to perform a specific task.

Functions allow you to easily reuse and execute these statements multiple times from various parts of a script, without having to manually repeat them.

Note that executing, calling, running, and invoking a function essentially mean the same thing and are often used interchangeably.

Declaring and executing functions

In JavaScript, functions are declared using the function keyword:

function functionName() {  statements}

Where:

• functionName is the name of the function.

• () are delimiters used to list function parameters.

• {} are delimiters used to encapsulate the function's statements, also called the body.