How can I check if a variable exist in JavaScript?

Question

I am not asking if the variable is undefined or if it is null. I want to check if the variable exists or not. Is this possible?

Answer 1

I use this function:

function exists(varname){
    try {
        var x = eval(varname);
        return true;
    } catch(e) { return false; }
}

Hope this helps.