jQuery: substitute (concatenated) button value with variable string

Question

So, I have a button whose value is concatenated from variables and strings:

$('#btn1').attr('value','question'+currid+'ans1').button('refresh');

This will return something like question5ans1, for example. Now, at the top of the javascript document, this value exists as a variable with a string associated, like this:

var question5ans1 = "Sydney";

The problem is that the button displays "question5ans1" instead of "Sydney". Is there any way to fix/change that?

Answer 1

Use eval to evaluate the string as var.

$('#btn1').attr('value', eval('question'+currid+'ans1')).button('refresh');

Instead of eval, a better solution is to have such var in a object like below,

var questions = {'question5ans1' : 'Sydney' };

and in the function,

$('#btn1').attr('value', questions['question'+currid+'ans1']).button('refresh');

Answer 2

If the variable is in the global scope, you can probably fetch it like this:

$("#btn1").val(window['question' + currid + 'ans1']);

Answer 3

You should attach these kinds of variables to an object as you cannot directly convert a string to a variable name. eval should not need to be used.

var q = {
    question3ans1: "London",
    question4ans1: "Tokyo",
    question5ans1: "Sydney"
};

$('#btn1').attr('value', q['question' + currid + 'ans1'] ).button('refresh');