Lesson 8: Functions: Basics

Functions can contain loops, arrays, and can also be passed parameters. A function runs only when it called and can be called multiple times with different parameters. Functions can return data as a result.

Defining Functions

• Functions are defined in JavaScript using the function keyword.
• After declaring the function keyword, you must define a function name, followed by parentheses () and braces containing the code for the function.

Example:

function myName is () { 

console.log("Hello,World");
}

Example 2:

function myFunction () { 

console.log ("I Love JavaScript")  
}

Functions with a parameter/argument

• Arguments are values that can be passed through a function. Parameter is another term used instead of argument. They are the same thing.
• When a function is being created, the arguments/parameters are defined inside the brackets, also known as parentheses, which are found after the function name.

Example:

function myFunction(myName){
console.log ("My name is" + myName)
}  

• Use the function name followed by parentheses to call a function.
• When passing parameters/arguments through a function, you must pass the correct number of parameters back.
• In the example above, we are passing one parameter (myName) through the function so the function will return only one parameter.

Example:

myFunction("Kevin")
}  

Example:

function myFruit (firstFruit,secondFruit){
console.log ("My favourite fruits are "+ firstFruit + "&" + secondFruit)
myFruit ("Apple", "Orange")
} 

In the example above, the function takes two arguments, “firstFruit” and “secondFruit”. When the function is called, you must pass a value for each of the two parameters listed in the function above.