Question

I would like to add property to an object with dynamical property name.

For this I’m using an eval(), but the compiler is returning : Unexpected token . Is what i’m doing possible, or eval() can’t be used for objects like str vars

Here is a bit of my code

    var options = {}; // Creating empty object
$("#selAdresse, #selCP, #selVille, #selPays, #selNom, #selDescription").live('change', function(){
    var opt = eval("var options.lol"); // The evil eval();
    opt = "Test"; // Trying to set options.lol = "test"
    console.log(options); // Returning an empty object... Nothing change
});

Answer 1

You don’t use var to add a property to an object. You use var to initially declare a variable:

var foo = {};

Adding properties is simple:

foo.bar = null;

If you have a string containing the property name, you use square bracket notation:

var propName = 'bar';
foo[propName] = null;

Edit:
Based on your comment to kbok, square bracket notation is what you want:

var options = {};
options[ $( this ).attr( 'id' ) ] = 'Test';

End Edit

To be specific to your question (though you shouldn’t be doing it and there are ways to avoid it), the syntax of your eval would look like:

eval( 'foo.bar = null;' );