Javascript: New variable name composed of value of another variable

Question

Easiest to explain by showing code:

var delta_selected = false;
var magma_selected = false;
var aqua_selected = false;

// Somewhere in my functions...
if (sumthing == 'sumthing1') {
    topic = 'delta';
} else if (sumthing == 'sumthing2') {
    topic = 'magma';
} else {
    topic = 'aqua';
}

// Then assign it (so if topic is delta, then delta_selected = true)
topic + "_selected" = true;

This last line isn't working. Syntax error.

I need help to figure out how to do this. Thanks!

Why not just set delta_seleted = true instead of topic = 'delta', etc... — jmaglio
– jmaglio, Commented Feb 23, 2012 at 19:16
If I could, I would. :D I only posted some of the code so you can't see why I cant just specify the name. — fahad
– fahad, Commented Feb 23, 2012 at 19:55

Marshall · Accepted Answer · 2012-02-23 19:12:40Z

3

try this

window[topic + "_selected"] = true;

answered Feb 23, 2012 at 19:12

Marshall

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Comments

user1106925 · Accepted Answer · 2012-02-23 19:15:41Z

3

Why use variables? Looks to me like you need a single structure that contains all your _selected values.

var selected = {
    delta:false,
    magma:false,
    aqua:false
};

then...

if (sumthing == 'sumthing1') {
    topic = 'delta';
} else if (sumthing == 'sumthing2') {
    topic = 'magma';
} else {
    topic = 'aqua';
}

selected[topic] = true;

answered Feb 23, 2012 at 19:15

user1106925

Comments

cjstehno · Accepted Answer · 2012-02-23 19:14:40Z

0

Take a look at the "eval()" function. You will probably end up with something like:

eval(topic + "_selected = true;")

But check the documentation to be sure.

Hope this helps.

answered Feb 23, 2012 at 19:14

cjstehno

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1 Comment

fahad Over a year ago

yes, I wouldn't want to use eval. Nice to know that I can do it like that though.

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