Question

ok I have this small code

http://jsfiddle.net/laupkram/yJtyD/

now its not really working. I had been following all the existing questions and answers here in SO but I can’t make this up.

I really want to call a function without using eval()

where i had been wrong?

Answer 1

You can’t execute a string directly. If the function specified by the string is defined globally you can access the function by

window[ fn ]();

So in your case this would transform your code to the following:

var fn = "imafunc";
if (typeof window[ fn ] === 'function') {
     window[ fn ]("hello world");
}

function imafunc(str) {
    alert(str);
}

If the function is defined only in another function’s scope, you have to resort to eval, which has some performance disadvantages and is generally considered bad practice (see, e.g., MDN).

PS: This won’t work in a jsFiddle as they use sandboxing, which is like defining imafunc() inside another function. You have to change the wrapping to use “no wrap”.