gistfile1.js

String.prototype.midTruncate = function(length, seperator){
  var left, right;
  length = length || 30, left = Math.ceil(length/2), right = Math.floor(length/2);
  seperator = seperator || '…';
  if (this.length<=(length+1)) return this.toString();
  return this.slice(0,left).strip()+seperator+this.slice(-right,this.length).strip();
};

"abcdefghijklmnopqrstuvwxyz".midTruncate(5)
// => "abc…yz"