How to convert a string value to a variable in javascript?

Question

var test1;
$(document).ready(function () {
    test1 = $("#test1ID").jQueryPlugin();
});

var test2;
$(document).ready(function () {
    test2 = $("#test2ID").jQueryPlugin();
});

...

This is done so we could just do test1.foo()... foo is a function inside the jQueryPlugin that is accessible using test1.foo() syntax;

So we have an array of strings which contains (test1, test2, ...) and we need to access foo() while on the loop:

for(i=0; i < theArrayOfStrings.length; i++){
    theArrayOfStrings[i].foo();
    //so here is the problem... we can't do test1.foo(), test2.foo() ... =(
}

Any idea on how to call function foo() while on the loop? Or can we convert a string value to a variable in javascript?

James · Accepted Answer · 2009-12-12 12:59:20Z

4

It might be worth creating an object to hold all your "tests":

var tests = {};

$(document).ready(function () {
    tests.test1 = $("#test1ID").jQueryPlugin();
    tests.test2 = $("#test2ID").jQueryPlugin();
});

for(i=0; i < theArrayOfStrings.length; i++){
    tests[theArrayOfStrings[i]].foo();
}

answered Dec 12, 2009 at 12:59

James

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2 Comments

Jronny Over a year ago

Nice idea, but the problem is what if I do not use loop to access foo() instead, I use a <select> and with the variable names ("test1", "test2") as the val per option... =(

bobince Over a year ago

That's not a problem at all. tests[document.getElementById('myselect').value].foo()

Community · Accepted Answer · 2017-05-23 12:07:05Z

2

eval() function is used to evaluate script in a string variable. For example :

var test1;
eval("test1=" + theArrayOfStrings[i]);
test1.foo();

But take a lok at this question before use When is JavaScript’s eval() not evil?

edited May 23, 2017 at 12:07

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answered Dec 12, 2009 at 12:48

Canavar

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2 Comments

Fabien Ménager Over a year ago

eval is not the solution to this problem

Jronny Over a year ago

this is working however... If this is the only choice, then I'll give it a go. Thanks!

bobince · Accepted Answer · 2009-12-12 14:27:28Z

1

If test1 is a global variable you can access it by name through the window object:

window[theArrayOfStrings[0]].foo();   // test1();

If it's not, eval is the only way, but I'd strongly advise avoiding eval in all circumstances. Using a lookup as in J-P's answer (+1) is much much more appropriate than selecting variable names.

edited Dec 12, 2009 at 14:27

answered Dec 12, 2009 at 13:27

bobince

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2 Comments

Eino Gourdin Over a year ago

Or more generally, you can use this instead of window, as: this['test1'](); // test1(); However, you still can only reference global variables, not local ones.

Eino Gourdin Over a year ago

Well, you can get the current function with arguments.callee. But you still couldn't access the function's local (inner) variables this way. So, you could declare the variables as the function's property, like: arguments.callee.test1 = ...; and then arguments.callee['test1'](). But this way comes back to J-P's proposition, which I think is the cleanest solution.

Adriaan Stander · Accepted Answer · 2009-12-12 12:38:04Z

0

Have you tried

$('#' + theArrayOfStrings[i]).foo();

Have a look at API/1.3/Selectors

answered Dec 12, 2009 at 12:38

Adriaan Stander

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3 Comments

Jronny Over a year ago

I just have no problem with jQuery selectors. theArrayOfStrings[i] is not an id that we need to call... =(

Adriaan Stander Over a year ago

So are you saying that theArrayOfStrings does not contain the test1, test2 etc that you wish to call? What does it contain then?

Jronny Over a year ago

test1, test2 are not ids... they are just variable that keeps the value of the element resulting from jQuery plugin integration.

Fabien Ménager · Accepted Answer · 2009-12-12 12:58:59Z

0

var test = [], n = 5;
$(document).ready(function () {
    for(var i=0; i < n; i++)
        test.push($("#test"+i+"ID").jQueryPlugin());
});

// the values in test won't be accessible before the document is loaded.

answered Dec 12, 2009 at 12:58

Fabien Ménager

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