Passing VAR from one function to another

madd74 · 05-Nov-2008, 03:43 AM #1

I have been attempting to understand how to pass a varible from one function to another, and with no luck. Here is my code

Code:

<html>
<head>
<script type="text/javascript">
function check(x) {
  document.getElementById("yes").value=x;
  if (x=="a") {
    var stuff = "your mom";
  }
  else if (x=="b") {
    var stuff = "your dog";
  }
  alert(stuff);
  return stuff;
}
</script>
<script type="text/javascript">
function showme(stuff)
  {
  alert(stuff);
  }
</script>
</head>
<body>

<form>
<input type="radio" name="browser" onclick="check(this.value)" value="a">first<br />
<input type="radio" name="browser" onclick="check(this.value)" value="a">second<br />
<input type="radio" name="browser" onclick="check(this.value)" value="b">third<br />
<br />
<input type="text" id="yes" size="2"><br />
<input type="button" onclick="showme(stuff)" value="show" />
</form>

</body>
</html>

Now, clicking on first or second will output "a" to the text id of "yes" and an alert box will say "your mom". Clicking on third will output "b" to the text id of "yes" and an alert box will say "your dog". Clicking show will do nothing. If I replace the showme(stuff) with showme("text here") then "text here" will show up when I click the show button. My research in using radio buttons show they are extremely difficult to get info from as compared to about everything else in a form (go figure). I appreciate any assistance in advance!

amanxman · 05-Nov-2008, 04:59 AM #2

Hey,

I'm by no way an expert on this kind of stuff, but initial thoughts are that when you're clicking show, it's going to show a variable dependant on what x is.

However, the variable 'stuff' is defined by the IFs BEFORE the X is defined.

In other works, think about it like this.

We run IF:
IF x = a, then say dog
IF x = b then say mum

We define x:
X = a

We ask it to say dog or mum

However, when the IF statement was run, X was no defined - X was defined AFTER the IF was run.

So,

We define x:
X = a

We run IF:
IF x = a, then say dog
IF x = b then say mum

We as it to say mum or dog. And it can because it knows what X is before the IF is run, and therefore it knows what to say.

Now, that's theoretically.

Practically I'm not sure sure. You might need to make the form submit itself, just parsing the variable (now defined) back into the IF statement.

Or, run the IF statement once it's been defined by the form, in the same session.

This might be total codswollop, and if it is, feel free to ignore me, but it does make half sense that the IF statement cannot be correctly working when X is not yet defined. If you run debug on the IF statement, you'll probably find it's coming out FALSE to both instances, i.e. x is not a and x is not b.

Perhaps the below will test this theory

Code:

function check(x) {
  document.getElementById("yes").value=x;
  if (x=="a") {
    var stuff = "your mom";
  }
  else {
    var stuff = "your dog";
  }
  alert(stuff);
  return stuff;
}

(note the second IF removed, and it is replaced with a simple ELSE)
If this shows your dog, it might indicate that your scripts are working ok, it's just that X is not defined when IF is running,

Let me know if i'm talking rubbish...!!!

Good luck

MMJ · 05-Nov-2008, 09:31 AM #3

in the onclick where you have showme(stuff) stuff is not a valid variable because it is private to the check function only.

To fix this you must have it global:

HTML Code:

<html>
<head>
<script type="text/javascript">
var stuff = ''; //GLOBAL VARIABLE
function check(x) {
  document.getElementById("yes").value=x;
  if (x=="a") {
    stuff = "your mom";
  }
  else if (x=="b") {
    stuff = "your dog";
  }
  alert(stuff);
  return stuff;
}
</script>
<script type="text/javascript">
function showme(stuff)
  {
  alert(stuff);
  }
</script>
</head>
<body>

<form>
<input type="radio" name="browser" onclick="check(this.value)" value="a">first<br />
<input type="radio" name="browser" onclick="check(this.value)" value="a">second<br />
<input type="radio" name="browser" onclick="check(this.value)" value="b">third<br />
<br />
<input type="text" id="yes" size="2"><br />
<input type="button" onclick="showme(stuff)" value="show" />
</form>

</body>
</html>

madd74 · 04:17 PM

Quote:

Originally Posted by amanxman

Hey,

I'm by no way an expert on this kind of stuff, but initial thoughts are that when you're clicking show, it's going to show a variable dependant on what x is.

However, the variable 'stuff' is defined by the IFs BEFORE the X is defined.

In other works, think about it like this.

We run IF:
IF x = a, then say dog
IF x = b then say mum

We define x:
X = a

We ask it to say dog or mum

However, when the IF statement was run, X was no defined - X was defined AFTER the IF was run.

So,

We define x:
X = a

We run IF:
IF x = a, then say dog
IF x = b then say mum

We as it to say mum or dog. And it can because it knows what X is before the IF is run, and therefore it knows what to say.

Now, that's theoretically.

Practically I'm not sure sure. You might need to make the form submit itself, just parsing the variable (now defined) back into the IF statement.

Or, run the IF statement once it's been defined by the form, in the same session.

This might be total codswollop, and if it is, feel free to ignore me, but it does make half sense that the IF statement cannot be correctly working when X is not yet defined. If you run debug on the IF statement, you'll probably find it's coming out FALSE to both instances, i.e. x is not a and x is not b.

Perhaps the below will test this theory

Code:

function check(x) {
  document.getElementById("yes").value=x;
  if (x=="a") {
    var stuff = "your mom";
  }
  else {
    var stuff = "your dog";
  }
  alert(stuff);
  return stuff;
}

(note the second IF removed, and it is replaced with a simple ELSE)
If this shows your dog, it might indicate that your scripts are working ok, it's just that X is not defined when IF is running,

Let me know if i'm talking rubbish...!!!

Good luck

Ignore? No way, I certainly appreciate the time you spend in looking into it for me

Actually the part of the script you tackled is working okay. X is properly defined by the onclick event of the radio button. You click first, then a textarea shows either "a or "b", and that works. At the same time, the alert will display from the check(x) function. So, by all standards, troubleshooting shows that the check(x) function is doing everything it is suppose to. The problem, which was tackled by MMJ, is that my variable is private, and I am attempting to make the var "stuff" be global, defined by the check(x), and used in showme(stuff).

So on that note, MMJ, I did what you said, and it makes sense looking at it now (I have forgotten a lot of basics on my programming skills

). Now, when you click on the "show" button, you get an alert box, however it is blank, which makes sense because that is how it is defined. Before, I was getting nothing. So I have progress, just not what I want yet.

So with the var stuff = ''; we have stuff defined as ''. I click on first through third, and each time I get a popup from check(x), and the textarea shows either a or b, just as it is suppose to. However, then stuff loses its a or b definition, and is showing as '' when I click on show

** EDIT **

BTW, amanxman, I did your suggestion just to see what would happen, and changing "else if" to "else" ended up breaking the function, it did nothing when I click on a radio button

Again, I am thankful for your brain input!

MMJ · 05-Nov-2008, 06:38 PM #5

Quote:

So with the var stuff = ''; we have stuff defined as ''. I click on first through third, and each time I get a popup from check(x), and the textarea shows either a or b, just as it is suppose to. However, then stuff loses its a or b definition, and is showing as '' when I click on show

Not quite following you.

At what point does it "lose its definition"?

madd74 · 05-Nov-2008, 08:11 PM #6

well, with the following

SCRIPT
var stuff
function check(x){
code
}
function showme(stuff){
code
}

Okay, so you click a radio button. Global VAR stuff now gets assigned a new value. When you click on the button, however, whatever VAR stuff was assigned is no longer there, it is null ''. The code changed to now reflect this:

Code:

<html>
<head>

<script type="text/javascript">
var stuff = '';
function check(x) {
  document.getElementById("yes").value=x;
  if (x=="a") {
    var stuff = "your mom";
  }
  else if (x=="b") {
    var stuff = "your dog";
  }
  alert(stuff);
  return stuff;
}
</script>

<script type="text/javascript">
  function showme(stuff)
  {
  alert(stuff);
  }
</script>

</head>
<body>

<form>
<input type="radio" name="browser" onclick="check(this.value)" value="a">first<br />
<input type="radio" name="browser" onclick="check(this.value)" value="a">second<br />
<input type="radio" name="browser" onclick="check(this.value)" value="b">third<br />
<br />
<input type="text" id="yes" size="2"><br />
<input type="button" onclick="showme(stuff)" value="show" />
</form>

</body>
</html>

Clicking on the "show" button brings up a blank alert box. It should also be noted that I attempted to define VAR stuff in its own text/javascript script, and I also attempted to move one function to the body and leave the other in the head and I still get the same results. The only part of this code that does not work, is that clicking show button is always blank.

Thanks again for everyone who has been looking into this for me.

MMJ · 06-Nov-2008, 09:54 AM #7

Doesn't seem to be that way when I test it.

When I first load the page and click on show it is empty because stuff is only an empty string.

However when I click on one of the radios then click on show it shows either your mom or dog, as it should do.

madd74 · 06-Nov-2008, 10:33 PM #8

hmm... that is absolutely crazy. I wonder if it has something to do with me testing with the tryit editor on w3schools. I will do this locally to see what I get, again, thanks a bunch!

** EDIT **

Hmm, nope, I get the same thing when I attempt it locally. I am using FF 3, so I am not sure if that has something to do with it. Just to verify, you get the alert box to show when you actually press the show button? Because it DOES give an alert box when you select a radio button, so I want to make sure we are on the same page

MMJ · 07-Nov-2008, 07:26 AM #9

Yeah, when I click show an alert box pops up, which makes sense because that is what the code tells it to do.

Make sure you are using my code and try a hard refresh if you think the page may be cached.

I am also using Fx 3.

madd74 · 06:26 PM

hmm... I am wondering if maybe it is, then. so the last code used is the one you checked and it worked with (post number 6)? if so, I will copy it, make an HTML file, and open it fresh on another computer that way I know it can't be a caching issue of any sort

** edit **

Okay, I actually see what I was doing different from your code, even though, I am not sure how that makes a difference since everything else worked fine. In my IF statements, I have "var stuff = " where you just have "stuff = " otherwise the code is identical. I even chopped your code, spacing wise, to be exactly like what I was using.

I always thought that "var thing = something" was the same as "thing = something"? Is it because it is being assigned in a function? If that is the case, do you know the reason it would actually work fine in the check(x) function? Does "var stuff = value" not store properly in the global variable of stuff then? That is what I am getting out of it :mrgreen:

MMJ · 08-Nov-2008, 05:46 AM **#11**

var tells it to keep the variable private, so it isn't working on the global variable.

which means that the global variable will always be empty

btw, my code flattened like that because of some sort of forum bug, when i posted it it was fine.

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