Javascript String truncate(capLength)

String.prototype.truncate = function(capLength){

 var trunc = '..';
 var output = this;

 if(typeof capLength !== 'number'){
  console.log('Arg must be a number type. No truncation made.');
  return output;// w  w w .j  ava 2  s.  c o  m
 }
 
 if(output.length > capLength){
  

   if(output[capLength-1] === ' '){ //dont trunc after an empty space, looks ugly
       capLength -= 1;
       
      }

      if(output[capLength-2] === ' ' || output[capLength-3] === ' '){ // dont trunc on a single/ double letter. looks ugly
       if(output[capLength-2] === ' '){
        capLength -= 2;
       }else{
        capLength -= 3;
       }
       
       }

   output = output.substring(0, capLength) + trunc;

 }
 else if(output.length === capLength){
  return output;
 }

 return output;
}