How to access javascript variable value by creating another variable via concatenation?

Question

Please have a look on the following code -

var abc_text = "Hello";
var def_text = "world";

function testMe(elem) {
    var xyz = elem+"_text";
    alert(xyz);
}

testMe("abc");
testMe("def");

I am trying to pass prefix to a function and the try to print some pre-defined values by concatenating. But the above example just prints "abc_text" and "def_text" .. instead of "Hello" and "world". How can I get it working?

Thank you.

EDIT

I am using Jquery.

This all sounds like the wrong approach. Why do you need variable variable names? — Gareth
– Gareth, Commented Jun 14, 2009 at 15:32

Jonathan Fingland · Accepted Answer · 2009-06-14 15:27:32Z

6

in this case use

var xyz = window[elem+"_text"];

answered Jun 14, 2009 at 15:27

Jonathan Fingland

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8 Comments

Matthew Flaschen Over a year ago

This (or alternately eval) is right. But wbdvlpr, note that it's rarely necessary to do this in well-written code.

Jonathan Fingland Over a year ago

eval is evil. eval should only ever be used in the rarest of situations. It is far too easy to get code injected from other sources.

Shog9 Over a year ago

@Jonathan: uh... well, no. It's only easy if you're accepting input from untrusted sources and then blindly passing it to eval(). But it's slow and in this case unnecessary; surely that's reason enough!

TigerTiger Over a year ago

@Jonathan Fingland - yes, it works. But associative array seems better to me. Thanks.

Jonathan Fingland Over a year ago

@wbdvlpr, oh I agree. the question as asked is solved by the window[] method, but the associative array method is better practice overall

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erenon · Accepted Answer · 2009-06-14 15:31:40Z

4

You can eval xyz, but it's better to store abc_text and def_text in associative array or in object;


var text = {"abc" : "Hello", "def" : "Word"};

answered Jun 14, 2009 at 15:31

erenon

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2 Comments

Jonathan Fingland Over a year ago

just to make erenon's point clearer. it would be accessed using, for example, var xyz = text[elem];

TigerTiger Over a year ago

Thanks @erenon, and Thanks, again, Jonathan Fingland, for its usage code.

Amar · Accepted Answer · 2012-12-20 05:30:37Z

3

var test={"abc":"Hello", "def":"World"};

function testMe(elem) { 
    var xyz = test[elem];
    alert(xyz); 
} 

testMe("abc"); 
testMe("def");

answered Dec 20, 2012 at 5:30

Amar

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Comments

Eli · Accepted Answer · 2009-11-02 19:53:22Z

1

There is a pretty good write-up on Dynamic Variables in JavaScript here:

http://www.hiteshagrawal.com/javascript/dynamic-variables-in-javascript

answered Nov 2, 2009 at 19:53

Eli

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