JavaScript move an item of an array to the front

I want to check if an array contains "role". If it does, I want to move the "role" to the front of the array.

var data= ["email","role","type","name"];
if ("role" in data) data.remove(data.indexOf("role")); data.unshift("role")
data;

Here, I got the result:

["role", "email", "role", "type", "name"]

How can I fix this?

Answer

You can sort the array and specify that the value "role" comes before all other values, and that all other values are equal:

var first = "role";
data.sort(function(x,y){ return x == first ? -1 : y == first ? 1 : 0; });

Demo: http://jsfiddle.net/Guffa/7ST24/