Variable passage from an onChange event function

jackyn · Dec 26, 2002

hello
Could you help me,anticipate thanks Jack
Here is my Javascript,and my questions:
Why the global variables in the to_do() function
(j and toto) can be used only in the to_do()
function,and when they are external to the to_do()
function,they are declared undefined ,what I have
to do to see these variables in the whole script?

Why in the to_do() function, if I call an other
function (myfonc() ),it's not work, but the
alert(" &quot

function works correctly ?

<html>
<head>
<title> essai </title>
</head>

<body>
<script language = "JavaScript">
var toto,j; // global
var streams = new Array();
streams[0] = new makeStream("","","&quot

;
streams[1] = new makeStream("1","11","table1&quot

;
streams[2] = new makeStream("2","22","table2&quot

;

function makeStream(name1,name2,name)
{
this.name1 = name1;
this.name2 = name2;
this.name = name;
}

function to_do(s)
{
toto = s.options[s.selectedIndex].value;

if(toto == "1&quot

{
document.write("TABLE1_fonction&quot

; // ok
j=1;
myfonc(); // not ok
}
if(toto == "2&quot

{
//document.write("TABLE2_fonction&quot

;
j = 2;
alert("toto&quot

; //ok
}
}

document.writeln('<SELECT NAME="streams" onChange="to_do(this)">');

document.writeln('<SELECT NAME="streams" onChange="faire(this)">');
document.writeln('<OPTION VALUE="', streams[0].name1, '">', streams[0].name);
document.writeln('<OPTION VALUE="', streams[1].name1, '">', streams[1].name);
document.writeln('<OPTION VALUE="', streams[2].name1, '">', streams[2].name);
document.writeln('</SELECT>');

myfonc(x)
{
document.write("j:",j);} // not ok, j undefined
document.write("toto:",toto); // not ok, toto undefined
}

document.write("toto:",toto); // not ok, toto undefined ?
</script>
</body>
</html>

Tarwn · Dec 26, 2002

Your my_fonc function is expecting you to pass it a value of some sort (x). Try calling it like this and see what happens: my_fonc("a string&quot

or you could just take the 'x' out of your function declaration.

-Tarwn Experts are only people who have realized how much they will never know about a language.
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jackyn · Dec 26, 2002

thanks for answering

myfonc()
{
document.write("j:",j);} // not ok, j undefined
document.write("toto:",toto); // not ok, toto undefined
}

does not work !
j and toto are global

mggates39 · Dec 27, 2002

I see a couple of issues here. First the definition for myfonc is incomplete and has a typo in it.

function myfonc()
{
document.write("j:",j); // not ok, j undefined
document.write("toto:",toto); // not ok, toto undefined
}

notice the function and that I removed an extra close brace after the first line.

Also, remove the second document.write("<SELECT ... as it is not needed.

Now to the logical flow. when the code executes for the first time, on page load, neither j nor toto has any value assigned, hence the 'undefined' when you write toto in the begining.

Once you select something from the drop down list, then both variables get a value.

Here is the modified code. See if it does what you want.

<html>
<head>
<title> essai </title>
</head>

<body>
<script language = "JavaScript">
var toto,j; // global
var streams = new Array();
streams[0] = new makeStream("","","&quot

;
streams[1] = new makeStream("1","11","table1&quot

;
streams[2] = new makeStream("2","22","table2&quot

;

function makeStream(name1,name2,name)
{
this.name1 = name1;
this.name2 = name2;
this.name = name;
}

function to_do(s)
{
toto = s.options[s.selectedIndex].value;

if(toto == "1&quot

{
document.write("TABLE1_fonction&quot

; // ok
j=1;
myfonc(); // not ok
}
if(toto == "2&quot

{
document.write("TABLE2_fonction&quot

;
j = 2;
alert("toto&quot

; //ok
}
}

document.writeln('<SELECT NAME="streams" onChange="to_do(this)">');

document.writeln('<OPTION VALUE="', streams[0].name1, '">', streams[0].name);
document.writeln('<OPTION VALUE="', streams[1].name1, '">', streams[1].name);
document.writeln('<OPTION VALUE="', streams[2].name1, '">', streams[2].name);
document.writeln('</SELECT>');

function myfonc()
{
document.write("j:",j); // not ok, j undefined
document.write("toto:",toto); // not ok, toto undefined
}

document.write("toto:",toto); // not ok, toto undefined ?
</script>
</body>
</html>

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Variable passage from an onChange event function

jackyn

Programmer

Tarwn

Programmer

jackyn

Programmer

mggates39

Programmer

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