makeFullName.js

/**
 * Build full name based on three string values, will not double space
 * @param  {string} f first name
 * @param  {string} m middle name
 * @param  {string} l last name
 * @return {string}   three strings joined by space
 */
function makePersonFullName(f,m,l) {
   var full_name = [];
   if(typeof f === "string" && f.trim().length > 0) { full_name.push(f); }
   if(typeof m === "string" && m.trim().length > 0) { full_name.push(m); }
   if(typeof l === "string" && l.trim().length > 0) { full_name.push(l); }

   return full_name.join(" ");
}