Learn about functions in Actionscript

posted: 12-03-06
author: PrimeVector
website: http://www.free-webmaster-resource.com
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Learn about functions in Actionscript

Functions are an essential part of any coding language and thus also in Flash Actionscript. They are very useful too and after you learn to use them you won't ever want to go back to not knowing about em. Functions sound like some StarTrek word that can mean a lot, but it isnt that hard to understand. Functions are like little engines that we can feed some data and the code inside the function will run when we actually trigger that function.

You create a function thisway:
functionName = function(value1,value2,etc,){
//CODE TO EXECUTE(like an engine)
}//closes the function

To call this function and thus feed that little engine you do this:
functionName(1,2,whatever);

That would trigger the function called functionName and plugs in 3 pieces of data which can be used in that function. You dont have to feed it data, but often thats what makes the function so cool, you feed it some data and you get the result returned to you. You could write some sort of routine like adding one variable to another only once and just include your function in your new document. Then you would immediately enable to use that function in other Flash files you might create.

Dont worry if this already sounds confusing because ill give you an example right now to clear this up.

Lets image you want to add two numbers and trace the output to the screen. You set it up like i did below.
var numberA = 10;
var numberB = 10;
var numberC = numberA + numberB;
trace(numberC);

This code is perfectly ok to use, but it is not scalable at all. Can you imagine writing it out every time you would have to have a few numbers. Lets create a function now to add those variables and call it to clear it up a bit. Lets name this function "addNumbers" and make it add two variables to eachother and return the result in a variable.
addNumbers = function(nrA,nrB){
var resultNr = nrA + nrB;
return resultNr
}

Now we can plugin any number for nrA or nrB and a result will be calculated. Then i used the return statement. With functions you can return a result if the function executes. Like when i would run the above example i could setup a new variable that would pickup that result. This is a very useful thing and enables you to use results to do other stuff.

This would add the numbers 1 + 10 and place 11 in variable "resNr".
var resNr = addNumbers(1,10);
trace(resNr); //traces 11

So to bring it back to that first little example:
var numberA = 10;
var numberB = 10;
var numberC = numberA + numberB;
trace(numberC);

We could now use our function to do this calculation like this.
var numberA = 10;
var numberB = 10;
This would add the the content of variable numberA to numberB: 10 + 10 and places the result in variable "numberC".
var numberC = addNumbers(numberA,numberB);
trace(numberC); //traces 20

Conclusion

Functions are here to make your life easier as a Flash developer. They enable you to write little engines you could use over and over in all your projects in a nice scalable way. If you have any questions please don't be shy and post a message in the forum.

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