How to create a variable from the value of another variable

Question

I need to create a variable from the value of another variable. As an example, this would be similar to how I would do this in VFP:

nameOfNextVar = "port_no_1";
eval(nameOfNextVar) = 7493

Then I will be able to say:

alert(port_no_1);

And the alert would give me 7493...

Is this possible in JavaScript???

TIA

Dennis

with eval : duplicate stackoverflow.com/questions/592630/… — malletjo
– malletjo, Commented Feb 21, 2012 at 19:15

ralfe · Accepted Answer · 2012-02-21 19:18:24Z

5

As a rule of thumb, you should try avoid eval when possible. However, if there is no other way, then you could do this:

nameOfNextVar = "port_no_1";
eval("var " + nameOfNextVar + " = 7493");
alert(port_no_1);

Hope that helps.

answered Feb 21, 2012 at 19:18

ralfe

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3 Comments

DKean Over a year ago

you rock... It is similar to how we do it in VFP, but this eval simply evaluates the text. In VFP you can say "print eval(nameOfNextVar)" and get back 7493. Can that be done in JavaScript??

ralfe Over a year ago

you could have eval("print " + nameOfNextVar );.

DKean Over a year ago

Actually, I tried it and id does the eval like VFP. Many thanks, @ralfe

ShankarSangoli · Accepted Answer · 2012-02-21 19:18:44Z

2

You can try something like this using JavaScript eval method. But using eval should be avoid if possible.

var nameOfNextVar = "port_no_1";
eval(nameOfNextVar + " = " + 7493);
alert(port_no_1);

http://jsfiddle.net/ngTQf/

Other alternative is to define properties on the object or a current instance. You can also use window to define variables or properties.

var nameOfNextVar = "port_no_1";
this[nameOfNextVar] = 7493;
alert(this.port_no_1);

window[nameOfNextVar] = 7493
alert(window.port_no_1);

http://jsfiddle.net/ngTQf/2/

answered Feb 21, 2012 at 19:18

ShankarSangoli

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2 Comments

DKean Over a year ago

Yes that works @ShankarSangoli Thank you for the quick response. And thanks for the fiddle!

DKean Over a year ago

And thank you for the alternatives. I think I like this option better: "window[nameOfNextVar] = ..." Good suggestion @ShankarSangoli

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