Saving reversed array to variable in javascript

I have an array of colors that I want the option to reverse. I have a toggle function that basically colors elements based on the array. If I throw a reverse variable then it reverses, but it reverses the global variable instead of the local variable.

var inc_colors = ['#000','#333','#888']; //global inc_colors

function toggleLegendColors(reverse){
  var reverse = reverse || false;
  var colors = inc_colors; //local colors
  if(reverse) colors.reverse(); //reverses inc_colors array as well as colors
  ...
}

How can I get the reversed global array without changing the global array?