Why is Jshint saying “variable already defined” in this if statement?

Question

I have this code:

 if ( something is true ) {
        var someVar = true;
    } else {
       var someVar = false;
    }

JsHint is saying that

Answer 1

This is due to hoisting.

In javascript, no matter where you define a new variable with var, it moves it to the top of the function you are in. Your code is producing the following above your if block at the top of the function:

var someVar;
var someVar;

Here is a tutorial to explain hoisting:

http://net.tutsplus.com/tutorials/javascript-ajax/quick-tip-javascript-hoisting-explained/