Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript

davidreyes2
davidreyes2
3,422 Points
Posted by davidreyes2
davidreyes2
3,422 Points

Function parenthesis

I am having trouble understanding what this piece of code means in the parenthesis.

function print (message) { document.write(message); }

What does "message" mean in this code? Can't I just use the "print" instead? Is there a difference?

Thanks.

1 Answer

Hayes McCardell II
Hayes McCardell II
643 Points

Parameters (arguments) go inside parenthesis. The function or method is print. The parameters (arguments) are what is being passed into the function.

if you 

alert("hello")

Hello is what is being passed to the alert method.

davidreyes2
davidreyes2
3,422 Points
davidreyes2
davidreyes2
3,422 Points

I understand alert, but I don't understand function, anyway to show me bit by bit?

Hayes McCardell II
Hayes McCardell II
643 Points 
function print (message) { 
   document.write(message); 
}

Unless message is a global variable (which are bad practice to use), the function print will not have access to the message. So in order for the code inside the function block to access message, you are passing it into the function as a parameter.

Whatever you want to have access to inside a function, it can be passed into the function as a parameter.

var message1 = "Hello";
var message2 = "World";

function print (message1, message2) {
  alert(message1 + " " + message2);
}