Appending string to variable name

Question

Is there a way to define variables in javascript to append them with another variable?

var card_id;
var card_links_grid+card_id;

I'd like the second variable to be appended with the information found in the first variable. For each card_id there will be a card_links_grid. I want to be able to access the card_links_grid variable for a specific card_id.

What's the right way to do that?

Normally when I think I need to change a variable name like this, I realise the easiest thing is to use an array instead — ChrisW
– ChrisW, Commented Nov 24, 2011 at 18:00
is this what you want? card_id=3 card_links_grid1 card_links_grid2 card_links_grid3 are 5,6 and 7 respt but when you card_links_grid+card_id you want it to return 7?? am i correct? — Baz1nga
– Baz1nga, Commented Nov 24, 2011 at 18:03

Quentin · Accepted Answer · 2011-11-24 18:02:13Z

8

The right was is to use either an array or an object, depending on if the id is going to be sequential or named.

var card_links_grid = {};
var card_id = "the_hanged_man";
card_links_grid[card_id] = "some value";

or

var card_links_grid = [];
card_links_grid.push("some value");

Variable variables are possible, but only with some hard to maintain and debug approaches that should be avoided. Use object types designed for the data structure you want to represent.

answered Nov 24, 2011 at 18:02

Quentin

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3 Comments

Boundless Over a year ago

I agree, it sounds like you should use an object. The above example should solve your problem.

user823527 Over a year ago

@Quentin Your suggestion is what I am looking for. I don't really have to append to the variable, since the object will allow me to retrieve information from card_links_grid with the card_id. I am testing this approach.

user823527 Over a year ago

An object worked. I have var card_id = "an id"; var anobject = new object; var card_links_grid = {}; card_links_grid[card_id] = anobject; This does what I need. Thanks.

Thein Hla Maw · Accepted Answer · 2011-11-24 18:16:55Z

3

I also recommend to use either array or object. But if you want to try with variable variable approach, you can try like this.

var card_id=1;
window['card_links_grid_' + card_id] = 'Marco';
document.write(window['card_links_grid_' + card_id]);

http://jsfiddle.net/Q2rVH/

Ref: http://www.i-marco.nl/weblog/archive/2007/06/14/variable_variables_in_javascri

answered Nov 24, 2011 at 18:16

Thein Hla Maw

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1 Comment

user823527 Over a year ago

I like the idea of an object.

Baz1nga · Accepted Answer · 2011-11-24 18:07:46Z

0

you could use the eval method for the same and get away with it.. something like this

var card_id=3;

var card_links_grid1=5,card_links_grid2=6,card_links_grid3=7;

eval("card_links_grid"+card_id) //will  o/p 7

P.S: If I ustood the question correctly

answered Nov 24, 2011 at 18:07

Baz1nga

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2 Comments

Quentin Over a year ago

You could, but it is slow and hard to debug. Use a proper data structure instead. There is almost never any reason to use eval.

Baz1nga Over a year ago

agreed! like I am all for using an associative array.. but I am answering to the question and nt suggesting an alternative.. its like people suggesting use jquery for most js questions here! zzzz..

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