I am learning java script for my OU course and have hit brickwall.

Can any kind fold help me please?

I am trying to write a function for this statement:
*switches current player
*
*function takes no argument
* if current player is 1, sets current player to 2
* otherwise sets current player to 1
*function returns no value

So far I have:

function switchCurrentPlayer()
{
	if (currentPlayer = 1)
	   {
	       currentPlayer = 2;
        }
            else
                {
                    currentPlayer = 1;
                }
}

Using this code to test I keep getting player 2

switchCurrentPlayer();
    document.write('player ' + currentPlayer + '<br>');
switchCurrentPlayer();
    document.write('player ' + currentPlayer + '<br>');

Anyone point me in the right direction? I am going a bit screen blind.

You need to be using == not =

= sets a value
== compares values

So your:
if (currentPlayer = 1)

is always returning true, and is setting current player to 1
(and then because it tests true (i.e. the script is able to set current player to 1) it is then being set to 2, by the enclosed code.

function switchCurrentPlayer()
{
	if (currentPlayer == 1)
	   {
	       currentPlayer = 2;
        }
            else
                {
                    currentPlayer = 1;
                }
}

Would work.

Neater code to do the same thing:

function switchCurrentPlayer() {
    currentPlayer == 1 ? currentPlayer = 2: currentPlayer = 1;
}

syntax for that is like:

[if this bit is true] ? [do this] : [if not, do this];

You sir, are a star! Thank you. This is all new to me and programming is not my strong point. Do you mind if I PM you for further help if needed?

 

I can offer biscuits with owl shapes on them as a reward!

Don't mind at all.

Though PB ad others might be more help if stuff gets advanced.

FORUM HELPFUL AWARD!

 

(worship)

^____^

<treasures>

<burries>

<berries>

<berets>

<berates>

<beartato>

Whilst what Xen says will work, it's possibly worth pointing out there is also a "===" operator.

The difference being that "==" will do type conversion to encourage a match, whilst "===" is stricter and requires same type too.

For example:

var a = 0;
var b = '0';
 
document.write(a==b);
document.write('\n');
document.write(a===b);

Some people argue you should always do === (unless you explicitly need == instead), though I'm not sure how much it matters (possibly a bit slower for non-matches, but most likely not worth worrying about).

Oh, and another thing:

currentPlayer == 1 ? currentPlayer = 2: currentPlayer = 1;

I would write that like this:

currentPlayer = (currentPlayer == 1) ? 2 : 1;

Because it's less repetitive, and thus less error-prone.

In this situation, you could also do "currentPlayer = 3-currentPlayer" which is even simpler (though more cryptic to understand).

And one more post, in a last ditch attempt to not have to go write a really boring report thing - this is all based on there only ever being two players.

It's good practise to write more modular code that can be used for other purposes - for this example, multi-player turn-based switching can be done with very little extra work:

function switchCurrentPlayer()
{
	currentPlayer++
 
	if ( currentPlayer > PlayerCount )
	{
		currentPlayer=1
	}
 
}

Set PlayerCount to any number, and this will cycle through them in order, whether there is 2 or 20 players.

(The "++" just means "add one")


Anyway, I better get on with wasting time doing what I'm supposed to be doing right now. :(

Don't show me these things when I am busy k thx :(

(giggle)

Wow, just wow.

 

Peter, why are you not ruling the world, or even just Britain by now?

 

The last email made a lot more sense to me and is in the style of scripting that the OU is teaching.

 

Come one peter, become that evil genius we all know and love.

Huh? I don't get that. Surely to cycle through you'll need a while or for loop?

Possibly badly worded - by "cycle through" I just meant each time called you'd get the appropriate next player - you'd call the function at the end of each player's turn (which in most games is a manually triggered event).

I don't know why. :(

Am I not allowed to be a non-evil one?