How to use string as Array name?

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April 4th, 2006, 10:00 AM

roamer

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How to use string as Array name?

a = new Array('a1','a2','a3');

function myfun1(haha){
tmp2 = haha;

for(i=0;i<tmp2.length;i++){
document.form1.mysel2.options[i]= new Option(tmp2[i],tmp2[i]);

}
}

...............
myfun1('a');
-------------------------------------------
When I alert(tmp2), a is displayed. But I found that tmp2[i] won't evaluate as a[i]. Because it just treat tmp2 as an array.
-------------------------------------------

Can anyone help? Thx.

April 4th, 2006, 01:12 PM

jsKid

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At first glance I would say that the problem is that you are
passing the array name as a string, instead of the object itself.

Code:

myfun1('a') --> myfun1(a)

But then it comes down to, you want to explicity access
the array via it's string name? Could you explain why you'd
want to do it this way?

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Last edited by jsKid : April 4th, 2006 at 01:14 PM.

April 4th, 2006, 03:22 PM

derelict

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you can get tricky...

I agree with jsKid, there doesn't seem to be any need to reference the array by a string containing its name. if you wanted to do this, it would be better to create a container with a string reference for the array, then use the string reference elsewhere... there's a couple ways to do this:

Code:

<html>
<head>
<title>JS wierdness</title>
<script type="text/javascript">
	var arrCont = new Array();
	arrCont['foo'] = new Array();
	arrCont['foo'][0] = 'arrrr foooooooohh onnnneee';
	arrCont['foo'][1] = 'arrrr foooooooohh twwwoooo';
	arrCont['bar'] = new Array();
	arrCont['bar'][0] = 'arrrr baaaaahhhrr onnnneee';
	arrCont['bar'][1] = 'arrrr baaaaahhhrr twwwoooo';
	var objCont = new Object();
	objCont['foo'] = new Array();
	objCont['foo'][0] = 'obbbby foooooooohh onnnneee';
	objCont['foo'][1] = 'obbbby foooooooohh twwwoooo';
	objCont['bar'] = new Array();
	objCont['bar'][0] = 'obbbby baaaaahhhrr onnnneee';
	objCont['bar'][1] = 'obbbby baaaaahhhrr twwwoooo';

	warr = 'foo';
</script>
</head>
<body>
given two arrays, 'foo' and 'bar', access them via string names by reference in either an array or object container:
<a id='linker' href="javascript:warr=='foo'?warr='bar':warr='foo';void(document.getElementById('linkor').firstChild.data=  'currently '+warr+', click to change');"><span id="linkor">currently foo, click to change</span></a><br><br>
<a href="javascript:alert(arrCont[warr][0])">alert from array container, part one</a><br>
<a href="javascript:alert(arrCont[warr][1])">alert from array container, part two</a><br><br>
<a href="javascript:alert(objCont[warr][0])">alert from object container, part one</a><br>
<a href="javascript:alert(objCont[warr][1])">alert from object container, part two</a><br>
</body>
</html>

but in both cases you're really using a string key in a container object (I think this works because arrays are objects and that object notation is allowed in JS). If you *must* access arrays by string reference, just build them as members of a collection (even if there's only one member) so that you can use this notation to find them.

Is this what you needed?

HTH - derelict

April 5th, 2006, 12:19 PM

roamer

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Yes, thank you, this is what I want. Though I am not fully know all the syntax (90% acheived), I think i can finish the rest of my code.

Actually, I would like to create 3 arrays, and by passing one argument to a function, it will extract the suitable array and return its values.

------------------
a = new Array('a1','a2','a3');
b = new Array('b1','b2','b3');
c = new Array('c1','c2','c3');

function myfun1(haha){
tmp2 = haha;

for(i=0;i<tmp2.length;i++){
document.form1.mysel2.options[i]= new Option(tmp2[i],tmp2[i]);

}
}
myfun1('b');

April 5th, 2006, 12:54 PM

derelict

garish grotesque gargoyle

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then this should work:

Javascript Code:

Original - Javascript Code

var arrCont = new Object;
// create an object to contain your arrays by reference
arrCont['a'] = new Array('a1','a2','a3');
arrCont['b'] = new Array('b1','b2','b3');
arrCont['c'] = new Array('c1','c2','c3');
// notice use of quotes around identifiers 'a','b', and 'c'
 
function myfun1(haha){
// input string 'b' comes in as var haha
 
tmp2 = arrCont[haha];
// notice *NO* quotes to deref input string from var context
// and that it's not a direct assign... we're grabbing from the array container arrCont
 
for(i=0;i<tmp2.length;i++){
document.form1.mysel2.options[i]= new Option(tmp2[i],tmp2[i]);
 
}
}
myfun1('b');
// notice quotes becuase we're passing the string identifier, not a variable

this should make your script work the desired way. If you have more questions about syntax or principles, please just ask

HTH - derelict

Comments on this post

roamer agrees!

How to use string as Array name?

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